History of Christianity
A crucified Jewish teacher, a persecuted sect that became an empire's official religion, and two thousand years of councils, schisms, and missions that carried it to every continent
Christianity began as a small movement around a Jewish teacher executed by Roman authority in the first century, its earliest years documented more thinly than most people assume. Within four centuries it went from outlawed sect to the Roman Empire's state religion, then split repeatedly over doctrine and power: East from West in 1054, and Western Christendom into dozens of competing churches after the Reformation. This timeline follows the historical record from the debated details of Jesus's life through the councils that defined Christian doctrine, the medieval papacy at the height of its power, the Reformation's fracture of Western Christianity, and the movement's twentieth-century shift from a European-centered faith to one whose numerical center now sits in the global South.
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- c. 30-33 CEDebated
Primary source · 2 sourceswhy?
Best source: Cornelius Tacitus, The Annals, Book XV, Chapter 44
Cited as a "primary" source (no stronger domain match).Jesus of Nazareth Is Crucified Under Pontius Pilate
No writing survives from Jesus's own lifetime. The Yale historian Elisabeth Schussler Fiorenza's observation, that one can glimpse only the historical shadow of Jesus and that the picture depends on the lens used, sums up a real limit in the evidence: the earliest sources are Paul's letters, written roughly two decades after the events they describe, and the Gospels, composed later still. Non-Christian writers of the following century, including the Roman historian Tacitus, treated Jesus's execution as a settled historical fact rather than a live question, recording that Christus was put to death by the procurator Pontius Pilate during the reign of Tiberius. Historians broadly accept that a Jewish teacher named Jesus was executed by Roman authority in Judea in this period; the theological claims made about him and many biographical details are separate questions the historical method cannot settle.
Why it matters: The gap between the thin first-century record and the fuller portrait that later Christian writing built matters because it shapes how historians, as opposed to theologians, can talk about Christian origins. Successive generations of scholars, from nineteenth-century rationalists through Albert Schweitzer's critique of them to the mid-twentieth-century revival of the question, have each reconstructed a different Jesus, a pattern that is itself part of the historical record.
How we know: The execution is independently attested by the non-Christian historian Tacitus writing around 116 CE and by the Christian sources Paul's letters and the Gospels, none of which are eyewitness documents written at the time.
Traditional date: c. 30-33 CE · Roman official who ordered execution: Pontius Pilate, procurator of Judea · Earliest surviving Christian writing: Paul's letters, from c. 49 CE onward · Non-Christian corroboration: Tacitus, Annals, Book 15 (c. 116 CE)
- c. 46-62 CEWell documented
Reputable source · 2 sourceswhy?
Best source: The Epistles of the Apostle Paul
The domain "rsc.byu.edu" is on our Reputable source registry.Paul Carries the Movement Across the Roman World
Paul, a Jew from Tarsus who had actively opposed the early Christian movement, described a conversion experience on the road to Damascus after which he began spreading the faith he had once tried to suppress. Over roughly four journeys covering an estimated 16,000 kilometers by land and sea, he founded and corresponded with Christian communities across Asia Minor and Greece, including Philippi, Thessalonica, Corinth, and Ephesus, before traveling to Rome as a prisoner appealing his case. His letters to these communities, some written directly and others likely composed by a scribe on his behalf, are the earliest surviving Christian documents, predating the written Gospels by roughly two decades. Of the thirteen New Testament letters that carry his name, scholars agree some were almost certainly written by him and debate whether he personally wrote several others, including the Pastoral Letters to Timothy and Titus, which some regard as composed by later followers writing in his name.
Why it matters: Paul's decision to carry the movement to non-Jewish communities across the Mediterranean, and to argue that gentile converts did not need to follow Jewish law, set Christianity on a path toward becoming a religion distinct from Judaism rather than a sect within it. His letters, written before any Gospel, are the oldest window historians have into how the earliest Christian communities understood their faith.
How we know: Paul's own letters are the primary source for his life and travels, supplemented by the Acts of the Apostles, a later narrative account whose historical reliability scholars weigh against the letters where the two accounts overlap or diverge.
Conversion location: Road to Damascus · Missionary journeys: Four, c. 46-57 CE, roughly 16,000 km · Letters attributed to him: 13, authorship of several debated · Final journey: c. 60-62 CE, to Rome as a prisoner
SourcesRelated timelines- Ancient Rome → · Paul's journeys and his final appeal to Rome unfolded inside the same imperial road and legal system covered in the Ancient Rome timeline.
- 64 CEWell documented
Primary source · 2 sourceswhy?
Best source: Cornelius Tacitus, The Annals, Book XV, Chapter 44
Cited as a "primary" source (no stronger domain match).Rome Blames the Christians for the Fire, and Nero Turns Persecution into Spectacle
After a fire devastated much of Rome in 64 CE, rumors blamed Emperor Nero himself for setting it. The historian Tacitus, writing about half a century later, recorded that Nero deflected the accusation onto Christians, a group Tacitus describes with open contempt but whose punishment he still found excessive. Those who confessed were arrested first, and their testimony led to the conviction of what Tacitus called an immense multitude, condemned less for arson than for hatred of the human race. Tacitus describes them being torn apart by dogs after being sewn into animal skins, crucified, or set alight to serve as human torches for nighttime illumination in Nero's gardens.
Why it matters: This is the first securely dated state persecution of Christians and the earliest independent, non-Christian account of the movement's existence in Rome. It set a precedent, invoked intermittently for the next two and a half centuries, that being a Christian could itself be treated as a capital offense by Roman authority.
How we know: Tacitus's Annals, written around 116 CE from a Roman senatorial perspective hostile to Christians, remain the principal source for Nero's persecution; no Christian account from within the same decade survives.
Fire of Rome: 64 CE · Source: Tacitus, Annals, Book 15, written c. 116 CE · Emperor: Nero (r. 54-68 CE) · Method of execution described: Crucifixion, mauling by dogs, burning
SourcesRelated timelines- Ancient Rome → · Nero's reign and the fire of 64 CE are covered in fuller imperial context in the Ancient Rome timeline.
- c. 65-100 CEDebated
Reputable source · 2 sourceswhy?
Best source: The Synoptic Gospels
The domain "rsc.byu.edu" is on our Reputable source registry.The Gospels Take Written Form, Decades After the Events They Describe
Most scholars hold that Mark was the earliest Gospel written, likely between 65 and 74 CE, and that Matthew and Luke both used Mark as a source, placing them roughly a decade or more later, in the 80s CE, with John usually dated last, around 90 to 100 CE. Brigham Young University's Religious Studies Center is candid that dating the synoptic Gospels is often educated guesswork, particularly for Matthew and Luke, since their dates depend on assumptions about Mark's date that cannot themselves be pinned down precisely. None of the four texts names its author within the body of the work; the traditional attributions to Matthew, Mark, Luke, and John became fixed only in the following century, once congregations that held more than one Gospel needed a way to tell them apart.
Why it matters: The gap of decades between the events and their written record, combined with uncertainty over authorship, is central to how historians read the Gospels: as documents shaped by the theological concerns and community memories of the late first century, not as contemporaneous transcripts, a distinction that does not settle questions of religious truth but does bear on historical method.
How we know: Dating rests on internal evidence, including whether a Gospel appears to describe the Jerusalem temple's destruction in 70 CE before or after the fact, and on which Gospels appear to draw material from which others.
Likely first Gospel: Mark, c. 65-74 CE · Matthew and Luke: c. 80-95 CE, both draw on Mark · John: Usually dated c. 90-100 CE · Named authorship inside the texts: None of the four Gospels names its author internally
- c. 111-113 CEWell documented
Primary source · 2 sourceswhy?
Best source: Pliny and Trajan
Cited as a "primary" source (no stronger domain match).A Roman Governor Asks the Emperor How to Handle Christians
Pliny the Younger, serving as governor of Pontus and Bithynia in Asia Minor, encountered Christians for the first time in his post and was unsure how imperial law applied to them. He wrote to Emperor Trajan describing his practice: he interrogated the accused, executed those who refused three times to renounce the faith, and forwarded Roman citizens to Rome for trial. He reported that Christians met before dawn on a fixed day, sang responsively a hymn to Christ as to a god, and bound themselves by oath against theft, adultery, and breach of faith rather than to any crime; torturing two female slaves described as deaconesses, he found nothing beyond what he called a depraved and excessive superstition. Trajan's reply told Pliny not to seek Christians out, to punish those who were denounced and convicted, but to pardon anyone who recanted by worshipping the Roman gods, and to disregard anonymous accusations entirely.
Why it matters: This exchange is the earliest surviving internal Roman government document on how to handle Christians, and Trajan's answer, punish if accused but do not hunt, became the empire's default policy for most of the following two centuries, applied unevenly by different governors and emperors until the systematic persecutions of the third and early fourth centuries.
How we know: The correspondence survives as Letters 10.96 and 10.97 in Pliny's own published collection of official letters from his governorship, an administrative record rather than a Christian composition.
Governor: Pliny the Younger, Pontus-Bithynia · Dates in office: 111-113 CE · Emperor: Trajan (r. 98-117 CE) · Trajan's rule: Do not seek out; punish if denounced and convicted; pardon if recanted
- c. 2nd century CEWell documented
Reputable source · 2 sourceswhy?
Best source: Christianity in the Second Century
The domain "rsc.byu.edu" is on our Reputable source registry.Second-Century Christians Argue Fiercely Over Who Jesus Was
Long before any council settled Christian doctrine, second-century Christians held sharply conflicting beliefs about basic questions: whether Jesus was fully divine, fully human, or some combination, and what kind of body he had. Marcion, an influential teacher eventually declared a heretic, argued for two separate gods, a harsh creator god of Jewish scripture and a higher god revealed uniquely through Jesus, and edited his own version of Luke's Gospel to remove material he thought contaminated by Jewish influence. Valentinus and other Gnostic teachers taught that salvation came through secret knowledge of the divine rather than through the death and resurrection central to what became mainstream Christian teaching. Brigham Young University's Religious Studies Center describes the category of Christian in this period as capacious, encompassing a genuine variety of beliefs and practices that varied by region.
Why it matters: This period shows that Christian doctrine was not handed down complete and then merely defended; it was worked out through direct competition between rival teachers and communities, a process that later councils like Nicaea and Chalcedon would try, with only partial success, to bring to a close.
How we know: Some second-century texts by Marcion and Gnostic teachers survive only in fragments quoted by their theological opponents, while others, including a cache of Gnostic writings found at Nag Hammadi, Egypt, in 1945, preserve original material in the movements' own words.
Period: 2nd century CE · Key disputed teacher: Marcion (excommunicated c. 144 CE) · Rival movement: Gnosticism (Valentinus and others) · Core dispute: Nature and divinity of Jesus, number of gods
- 303-311 CEWell documented
Primary source · 2 sourceswhy?
Best source: The Great Persecution
Cited as a "primary" source (no stronger domain match).Diocletian Launches the Empire's Last and Harshest Persecution
In February 303 CE, Emperor Diocletian ordered a newly built church at Nicomedia destroyed and issued the first of four edicts against Christians, commanding that churches be razed, scriptures burned by fire, and Christians holding positions of honor stripped of them, with Christian household slaves losing any prospect of freedom. Later edicts under Diocletian and his co-emperor Galerius ordered the imprisonment of clergy and, eventually, required all subjects, including women and children, to offer sacrifice to the Roman gods on pain of punishment. The persecution, the empire's most systematic and geographically widespread against Christians, continued under different regional emperors with varying severity until Galerius issued an edict of toleration in 311 CE, shortly before his death, followed two years later by Constantine and Licinius's Edict of Milan.
Why it matters: This was the last time the Roman state attempted to eliminate Christianity by force, and its failure, followed within a decade by imperial toleration and then favor under Constantine, marked one of the sharpest reversals of fortune for any religious movement in ancient history.
How we know: The main contemporary accounts come from the Christian writers Eusebius, in his Ecclesiastical History and Martyrs of Palestine, and Lactantius, who as an eyewitness in Nicomedia described the destruction of the church there and the successive edicts.
Started: February 303 CE, Nicomedia · Emperors: Diocletian, Galerius, Maximian, Constantius · Ended by: Galerius's edict of toleration, 311 CE · Followed by: Edict of Milan, 313 CE
SourcesRelated timelines- Ancient Rome → · Diocletian's wider administrative reforms of the late Roman Empire are covered in the Ancient Rome timeline.
- October 28, 312 CEDebated
Primary source · 2 sourceswhy?
Best source: Eusebius, Life of Constantine
Cited as a "primary" source (no stronger domain match).Constantine Sees a Sign Before Battle and Turns the Empire Toward Christianity
Before defeating his rival Maxentius at the Battle of the Milvian Bridge outside Rome on October 28, 312 CE, Constantine reported a sign that he credited with his victory. The bishop and historian Eusebius, writing decades later, described Constantine seeing a cross of light above the sun bearing the words conquer by this, followed that night by a dream in which Christ told him to make a military standard from the same symbol. The earlier writer Lactantius, who had direct contact with Constantine, described only a dream rather than a daytime vision. The Christian History Institute is direct that the truth of either account cannot be verified independently, though Constantine's subsequent decades of consistent favor toward the Christian church, including restoring confiscated church property, are not in doubt regardless of what happened the night before the battle.
Why it matters: Whatever actually occurred, Constantine's victory and his own account of divine favor marked the beginning of imperial patronage for a religion that had been persecuted within living memory, setting up the Edict of Milan the following year and, within decades, Christianity's rise to become the empire's dominant faith.
How we know: The two earliest accounts, by Lactantius writing within a decade of the battle and by Eusebius writing his Life of Constantine after the emperor's death in 337 CE, disagree on key details, which is itself part of the evidence historians weigh.
Battle: Milvian Bridge, October 28, 312 CE · Defeated rival: Maxentius · Earlier account: Lactantius: a dream · Later account: Eusebius: a vision of a cross
SourcesRelated timelines- The Byzantine Empire → · Constantine went on to found Constantinople, the city whose history the Byzantine Empire timeline follows for the next millennium.
- February 313 CEWell documented
Primary source · 2 sourceswhy?
Best source: The Edict of Milan
Cited as a "primary" source (no stronger domain match).The Edict of Milan Ends Christianity's Legal Persecution
Meeting in Milan in February 313 CE, the western emperor Constantine and the eastern emperor Licinius agreed on a policy of religious toleration across the Roman Empire, building on an earlier toleration edict issued by Galerius in 311 CE. The agreement, recorded in a letter Licinius sent to provincial governors, stated that Christians and everyone else should have full authority to observe whatever religion each preferred, so that no one should be denied the chance to devote himself to the religion he judged best suited to himself. The edict also ordered the restoration of property confiscated from Christians during the recent persecution, including places of worship, at public expense.
Why it matters: The Edict of Milan did not make Christianity the state religion, that step was still nearly seventy years away, but it ended the legal jeopardy Christians had lived under intermittently for two and a half centuries and opened the door to the imperial patronage that would remake the church's fortunes within a single generation.
How we know: The edict survives quoted in full within Lactantius's contemporary work On the Deaths of the Persecutors and in Eusebius's Ecclesiastical History, two independent Christian sources writing close to the event.
Date: February 313 CE · Issued by: Constantine (west) and Licinius (east) · Built on: Galerius's toleration edict of 311 CE · Also ordered: Restoration of confiscated church property
- 325 CEWell documented
Primary source · 2 sourceswhy?
Best source: The Creed of Nicaea
Cited as a "primary" source (no stronger domain match).The Council of Nicaea Writes the First Creed
Constantine convened bishops from across the empire at Nicaea in 325 CE to resolve a dispute that had split the church: the Alexandrian priest Arius taught that Christ, as the Son, was created by God the Father and therefore not equal to him or co-eternal, a position most bishops at the council rejected. The council produced the Nicene Creed, declaring belief in Christ as of one substance with the Father, begotten not made, and formally anathematizing anyone who taught that the Son was created or of a different substance from the Father. The council also issued twenty canons on church discipline, covering matters from clerical conduct to the standing of bishops.
Why it matters: Nicaea was the first attempt to settle Christian doctrine through an empire-wide gathering of bishops backed by imperial authority rather than through informal consensus, and the Arian controversy it aimed to end persisted in various forms for decades afterward, showing how difficult that kind of doctrinal closure actually was to achieve.
How we know: The Nicene Creed and the council's twenty canons survive in multiple manuscript copies preserved through the Nicene and Post-Nicene Fathers textual tradition, cross-checked against later church historians who describe the council's proceedings.
Convened by: Emperor Constantine · Year: 325 CE · Rejected teaching: Arianism (Christ as created, not co-eternal) · Output: The Nicene Creed, 20 canons
- February 27, 380 CEWell documented
Primary source · 2 sourceswhy?
Best source: The Theodosian Code, Book XVI
Cited as a "primary" source (no stronger domain match).Theodosius Makes Nicene Christianity the Empire's Official Religion
Emperor Theodosius I, together with co-emperors Gratian and Valentinian II, issued an edict in 380 CE commanding that all peoples under their rule should hold to the religion handed down by the apostle Peter to the Romans, professed by Pope Damasus and by Peter, bishop of Alexandria, and affirming belief in the Father, Son, and Holy Spirit as equal in majesty within a single Trinity. The edict, recorded in the Theodosian legal code, named this Nicene position the only faith entitled to be called Catholic and threatened those who dissented with what it called the judgment of divine condemnation, later followed by concrete legal penalties against groups like the Arians. Where the Edict of Milan in 313 CE had granted toleration to all religions, this edict went further, establishing a single specific Christian creed as the empire's law.
Why it matters: This edict turned Nicene Christianity from a tolerated and imperially favored religion into the compulsory state religion of the Roman Empire, ending the era of pagan and heterodox Christian practice as a legally protected option and setting the template European states would follow for religious establishment for the next fourteen centuries.
How we know: The edict is preserved in Book 16 of the Codex Theodosianus, the official compilation of Roman imperial law completed in 438 CE, an administrative record rather than a religious composition.
Date: February 27, 380 CE · Issued by: Theodosius I, Gratian, Valentinian II · Recorded in: Codex Theodosianus, Book 16.1.2 · Effect: Made Nicene Christianity the sole legal state religion
- 413-426 CEWell documented
Primary source · 2 sourceswhy?
Best source: Augustine: The City of God
Cited as a "primary" source (no stronger domain match).Augustine Answers Rome's Fall With Two Cities
When Alaric's Visigoths sacked Rome in August 410 CE, the first time the city had fallen to a foreign army in nearly eight hundred years, critics blamed the disaster on Rome's abandonment of its old gods for Christianity. Augustine, bishop of Hippo in North Africa, spent over a decade, from 413 to 426 CE, answering that charge in The City of God, arguing that two cities have been formed by two loves: the earthly city by love of self carried to contempt of God, and the heavenly city by love of God carried to contempt of self. Augustine argued the earthly city, built on human glory and power, was inherently unstable and prone to the wars and conflict that had always afflicted it long before Christianity existed, while the heavenly city's citizens lived as strangers within earthly kingdoms, bound instead to an eternal home outside history's fluctuations.
Why it matters: The City of God separated Christian identity from the fate of any specific earthly power, including Rome itself, an argument that let Christianity survive intellectually and institutionally as the Western Roman Empire collapsed around it over the following decades, and it became one of the most influential works of Christian political thought for the next fifteen centuries.
How we know: The City of God survives complete in the manuscript tradition and is one of Augustine's best-attested works, along with his Confessions, both preserved and copied continuously since late antiquity.
Rome sacked by: Alaric and the Visigoths, August 410 CE · Author: Augustine, Bishop of Hippo · Written: 413-426 CE · Central argument: Two cities: earthly (self-love) and heavenly (God-love)
SourcesRelated timelines- Ancient Rome → · The sack of Rome in 410 CE and the empire's final decades in the west are covered in the Ancient Rome timeline.
- 451 CEWell documented
Primary source · 2 sourceswhy?
Best source: The Council of Chalcedon, Session V, Definition of Faith
Cited as a "primary" source (no stronger domain match).The Council of Chalcedon Defines Christ's Two Natures, and Splits the Church Doing It
The Fourth Ecumenical Council, meeting at Chalcedon in 451 CE, tried to settle a dispute over how Christ's divine and human natures related to each other, rejecting both Nestorius's teaching of two separate persons in Christ and Eutyches's opposite claim that Christ had only a single, divine nature after the incarnation. The council's Definition of Faith declared Christ to be acknowledged in two natures, without confusion, without change, without division, without separation, united in one person and subsistence while each nature kept its own distinct properties. Large areas of the Christian East, including the Coptic church in Egypt and the church in Ethiopia, rejected this formula and broke communion with Constantinople and Rome, forming what are now called the Oriental Orthodox churches, a division that persists today.
Why it matters: Chalcedon shows that even a council convened specifically to produce unity could instead produce a permanent new division, and the split it caused between Chalcedonian and non-Chalcedonian churches weakened the Byzantine Empire's hold on Egypt and Syria in the centuries before those regions came under Muslim rule.
How we know: The council's Definition of Faith and acts survive in the conciliar record compiled and transmitted through the Greek and Latin manuscript tradition of ecumenical council documents.
Year: 451 CE · Rejected views: Nestorianism (two persons), Eutychianism (one nature) · Formula: Two natures, unconfused, unchanged, undivided, unseparated · Result: Oriental Orthodox split (Coptic, Ethiopian, others)
SourcesRelated timelines- The Byzantine Empire → · The Chalcedonian split weakened Byzantine control over Egypt and Syria; see the Byzantine Empire timeline for how that played out over the following centuries.
- c. 530 CEWell documented
Primary source · 2 sourceswhy?
Best source: The Rule of St. Benedict
Cited as a "primary" source (no stronger domain match).Benedict Writes a Rule and Founds Western Monasticism's Template
Benedict of Nursia, born around 480 CE, began his own monastic life at Subiaco before founding a monastery at Monte Cassino in 529 CE, where around 530 CE he composed the Rule of Saint Benedict, a set of guidelines governing communal monastic life drawing on earlier, less organized monastic traditions. The Rule opens by describing the monastery as a school for the Lord's service, organized so that nothing in it would be excessively severe or burdensome, and it structured each day around manual labor, private reading, and a fixed cycle of communal prayer, from Matins before dawn through Compline at nightfall. Monks bound themselves to the monastery for life under vows of poverty, chastity, and obedience to an abbot elected by the community, and the Rule spread gradually to other monastic houses across Western Europe over the following centuries, eventually becoming the dominant model for Western monasticism.
Why it matters: Benedictine monasteries became the primary centers of literacy, manuscript copying, and organized agriculture across large parts of early medieval Western Europe, and the Rule's balance of prayer, labor, and communal structure shaped how the Western church would organize religious life for the next thousand years.
How we know: The Rule of Saint Benedict survives in numerous manuscript copies from across medieval Europe, and archaeological remains at Monte Cassino and other Benedictine foundations corroborate the monastery's early establishment.
Author: Benedict of Nursia (c. 480-547 CE) · Rule composed: c. 530 CE, Monte Cassino · Core vows: Poverty, chastity, obedience · Daily structure: Manual labor, reading, and eight fixed prayer times
- 597 CEWell documented
Primary source · 2 sourceswhy?
Best source: Gregory I: Letter to Mellitus
Cited as a "primary" source (no stronger domain match).Pope Gregory the Great Sends Missionaries to Convert England
Before becoming pope, Gregory the Great had already asked Rome's bishop to send missionaries to Britain to convert the English; once elected pope himself, he acted on that same interest and sent a monk named Augustine with a group of companions to the kingdom of Kent in 597 CE, where King Ethelbert received them. Gregory's instructions to the mission, recorded in a letter to the missionary Mellitus, told Augustine not to destroy English temples but only the idols inside them, and to purify the buildings with holy water and install altars and relics of the saints there instead, reasoning that the people would abandon their old error in a place already dear and familiar to them. The mission succeeded in converting Ethelbert and established a permanent Christian foothold in England, with Augustine becoming the first Archbishop of Canterbury.
Why it matters: Gregory's strategy of converting buildings rather than demolishing them became a recurring missionary technique used well beyond England, and the mission itself restored organized Christianity to England more than a century and a half after Roman rule had ended there, planting the church that would later send its own missionaries onward into continental Europe.
How we know: The mission is described in Bede's Ecclesiastical History of the English People, written in the early 8th century drawing on earlier records, and Gregory's own letter to Mellitus survives independently as a papal register document.
Pope: Gregory I (Gregory the Great), r. 590-604 CE · Missionary sent: Augustine of Canterbury · Year: 597 CE · Destination: Kingdom of Kent, England
- December 25, 800 CEWell documented
Primary source · 2 sourceswhy?
Best source: Einhard: The Life of Charlemagne
Cited as a "primary" source (no stronger domain match).Charlemagne Is Crowned Emperor, Reviving Rome in the West
On Christmas Day, 800 CE, Pope Leo III crowned the Frankish king Charlemagne as Emperor and Augustus during Mass at St. Peter's Basilica in Rome, reviving an imperial title in the West that had lapsed more than three centuries earlier. Charlemagne's own biographer and courtier, Einhard, insisted the king had such an aversion to the titles that he would not have entered the church that day, a great feast, had he foreseen the pope's plan, though Einhard's account, written to defend Charlemagne's reputation, is itself a source historians read with some caution. Whatever Charlemagne's real reaction, he went on to accept the title, later securing recognition from the Byzantine emperors in the east, whose own claim to the Roman imperial title Charlemagne's coronation directly challenged.
Why it matters: The coronation tied the Frankish monarchy's legitimacy directly to papal approval, establishing a precedent, invoked and contested for centuries afterward, that only the pope could confer the imperial crown, and it created the political entity that later became known as the Holy Roman Empire.
How we know: Einhard's Life of Charlemagne, written by someone who served at Charlemagne's own court, records the coronation directly, and the event is independently confirmed in modern historical scholarship on the period.
Date: December 25, 800 CE · Crowned by: Pope Leo III · Location: St. Peter's Basilica, Rome · Source: Einhard, Life of Charlemagne
- July 16, 1054 CEWell documented
Primary source · 2 sourceswhy?
Best source: The Great Schism
Cited as a "primary" source (no stronger domain match).The Great Schism Splits Rome and Constantinople
Centuries of theological and political friction between the Latin West and Greek East, over questions including the filioque addition to the Nicene Creed and the use of unleavened bread in the Eucharist, came to a head after Norman conquerors in southern Italy suppressed Greek church practices there. Patriarch Michael Cerularius of Constantinople retaliated by pressuring Latin churches in his own city to adopt Greek customs, prompting Pope Leo IX to send a delegation led by Cardinal Humbert of Silva Candida. After a cold reception, Humbert strode into Hagia Sophia during a service on July 16, 1054 CE and placed a bull of excommunication against Cerularius on the altar; the patriarch responded within days by excommunicating Humbert and the other legates in turn.
Why it matters: Modern historians agree no single event caused a clean, immediate break, and relations between individual eastern and western churches remained workable in places for some time afterward, but this mutual excommunication became the symbolic starting point historians call the Great Schism, a division between the Catholic and Orthodox churches that the two sides did not formally lift until 1965.
How we know: The events of July 1054 CE are recorded in the Orthodox Church in America's own institutional history of the schism and corroborated by independent Western and Byzantine accounts of Humbert's mission and Cerularius's response.
Date: July 16, 1054 CE · Papal legate: Cardinal Humbert of Silva Candida · Patriarch: Michael Cerularius · Anathemas lifted: 1965, by Pope Paul VI and Patriarch Athenagoras I
SourcesRelated timelines- The Byzantine Empire → · The Byzantine Empire timeline covers the Great Schism from Constantinople's side, including the political tensions with the Normans that set it off.
- November 27, 1095 CEWell documented
Reputable source · 2 sourceswhy?
Best source: Council of Clermont
The domain "worldhistory.org" is on our Reputable source registry.Pope Urban II Launches the Crusades
Responding to an appeal from the Byzantine emperor Alexios I Komnenos for military help against advancing Seljuk Turks, Pope Urban II preached an open-air sermon at the Council of Clermont in France on November 27, 1095 CE, calling on Western Christians to march to Jerusalem and take it from Muslim rule. Urban promised full remission of sins to anyone who took up the cross, an offer on a scale no earlier pope had made, and the appeal drew tens of thousands of knights and commoners within months, launching the First Crusade the following year. The movement Urban started continued in repeated waves for nearly two centuries, reshaping relations between Western Christendom, the Byzantine Empire, and the Islamic world across the eastern Mediterranean.
Why it matters: Clermont fused military service to the forgiveness of sin in a way that became the template for every later crusade, and it opened two centuries of warfare, negotiation, and cultural exchange between Christian Europe and the Muslim Middle East whose consequences, including deep and lasting mistrust on multiple sides, outlasted the crusading movement itself by many centuries.
How we know: No verbatim transcript of Urban's speech survives; historians rely on several independent chronicle accounts written within a decade or two of Clermont that agree on its core content while differing in wording.
Date: November 27, 1095 CE · Location: Council of Clermont, France · Trigger: Byzantine emperor Alexios I Komnenos's appeal for troops · Offer: Full remission of sins for those who took the cross
Sources- World History Encyclopedia. Council of Clermont · reference
- World History Encyclopedia. Alexios I Komnenos · reference
Related timelines- The Crusades → · The full campaign history of the Crusades, from Manzikert in 1071 through the fall of Acre in 1291, is covered in its own dedicated timeline.
- The Rise of Islam → · The Muslim states the Crusaders fought and negotiated with are covered from their own side in the Rise of Islam timeline.
- 1266-1273 CEWell documented
Primary source · 2 sourceswhy?
Best source: Thomas Aquinas: Summa Theologiae
Cited as a "primary" source (no stronger domain match).Thomas Aquinas Fuses Faith With Reason in the Summa Theologiae
Thomas Aquinas, a Dominican friar teaching at the newly founded universities of Paris and elsewhere, composed the Summa Theologiae between 1266 and 1273 CE, a systematic work intended, in his own words, to instruct beginners as well as the advanced in Christian teaching. Aquinas drew heavily on the newly recovered works of Aristotle, whose logical methods had become available to Western scholars mainly through translations from Arabic and Greek in the preceding two centuries, arguing that reason and revelation both led toward the same truth rather than standing in conflict. The work's Five Ways offered five separate logical arguments for God's existence, the first reasoning from the observable fact of motion in the world to the necessity of an unmoved first mover.
Why it matters: Aquinas's synthesis of Aristotelian philosophy with Christian theology became the intellectual foundation of scholasticism, the dominant method of medieval university education, and the Summa remained the single most authoritative work of Catholic theology for the following seven centuries.
How we know: The Summa Theologiae survives in numerous medieval manuscript copies and was widely taught and commented on within Aquinas's own lifetime and immediately afterward at the universities of Paris and elsewhere.
Author: Thomas Aquinas (1224/1225-1274) · Written: 1266-1273 CE · Order: Dominican · Key feature: The Five Ways, arguments for God's existence
- 1517 CE onwardWell documented
Reputable source · 2 sourceswhy?
Best source: 1517 Luther Posts the 95 Theses
The domain "christianhistoryinstitute.org" is on our Reputable source registry.Martin Luther Challenges the Church, Splitting Western Christianity
In 1517 CE the German monk Martin Luther publicly challenged the Catholic Church's sale of indulgences, payments believed to reduce punishment for sin, opening a dispute over church authority, salvation, and scripture that spread rapidly across Europe and split Western Christianity into competing Protestant and Catholic churches within a generation. The movement Luther began was quickly followed by parallel reform efforts under other leaders, including John Calvin in Geneva and the separate English Reformation under Henry VIII, each producing distinct church traditions rather than a single unified Protestant alternative to Rome.
Why it matters: The Reformation ended a millennium in which Western Europe had, with only partial exceptions, shared a single church, replacing it with a permanent set of competing Christian traditions whose doctrinal and political divisions shaped European wars, colonization, and religious life for centuries afterward.
How we know: The Reformation's causes, key figures, and spread across Europe are covered in full in this platform's dedicated Reformation timeline, drawing on Luther's own writings and the records of the reform movements that followed him.
Started: 1517 CE, Wittenberg · Key figure: Martin Luther · Parallel movements: Calvin (Geneva), Henry VIII (England) · Result: Permanent split of Western Christianity into rival churches
SourcesRelated timelines- The Protestant Reformation → · The Reformation's full causes, key figures, and spread across Europe are covered in its own dedicated timeline.
- 1545-1563 CEWell documented
Primary source · 2 sourceswhy?
Best source: Ten Rules Concerning Prohibited Books
Cited as a "primary" source (no stronger domain match).The Council of Trent Answers the Reformation With Its Own Reform
Meeting across three separate periods between 1545 and 1563 CE, the Council of Trent formed the Catholic Church's central response to the Protestant Reformation, reaffirming disputed doctrines including the necessity of both faith and good works for salvation, against Luther's teaching of faith alone, and the authority of church tradition alongside scripture. Alongside doctrine, the council issued disciplinary decrees aimed at reforming clerical abuses, including absentee bishops, and Trent's associated Index of Prohibited Books set out formal rules for restricting Catholic access to texts judged heretical or morally corrupting, including works that were, in the rules' own words, absolutely prohibited when they professedly dealt with lascivious or obscene material.
Why it matters: Trent gave the Catholic Church a clear, unified doctrinal and disciplinary answer to Protestant challenges for the first time, and the reforms and definitions it produced governed Catholic belief and practice for four centuries, until the Second Vatican Council revisited many of the same questions in the 1960s.
How we know: The council's canons, decrees, and disciplinary rules survive as an official published record ratified by the papacy, distinct from later historical summaries of what the council decided.
Dates: 1545-1563 CE, three sessions · Key doctrine reaffirmed: Faith and works both necessary for salvation · Disciplinary reform: Clerical residence, seminary training · Related measure: Index of Prohibited Books
SourcesRelated timelines- The Protestant Reformation → · Trent's doctrinal responses directly answered positions laid out by Luther and Calvin, covered in the Reformation timeline.
- 1540s-1600s CEWell documented
Primary source · 2 sourceswhy?
Best source: St. Francis Xavier's Letter from Japan, 1552
Cited as a "primary" source (no stronger domain match).Jesuit Missionaries Carry Christianity to Asia and the Americas
The Jesuit order, founded in 1540 CE partly as a response to the Reformation, sent missionaries across Catholic colonial and trade networks to Asia and the Americas. Francis Xavier, who had already worked in India and Japan, wrote in 1552 CE that he hoped to enter China that same year and penetrate even to the emperor himself, expressing hope that God would soon provide free entrance to China not only to the Jesuits but to religious orders of every kind; he died that December on an island off the Chinese coast without ever gaining entry. Decades later, Matteo Ricci succeeded where Xavier had not, arriving in China in 1583 CE and adopting a strategy, developed under the Jesuit visitor Alessandro Valignano, of presenting himself as a Confucian-educated Western scholar rather than a foreign disruptor, a method of cultural accommodation that helped the China mission gain a foothold among the educated elite.
Why it matters: Jesuit missionary strategy, especially Ricci's accommodation of local elite culture rather than demanding its rejection, set a pattern for how Christianity spread into societies with their own long-established religious and philosophical traditions, a pattern that later missionary movements sometimes followed and sometimes explicitly rejected.
How we know: Xavier's own letters, preserved and published by the Jesuit order, and later Jesuit records of Ricci's mission provide direct documentary evidence for both men's approaches and outcomes.
Jesuit order founded: 1540 CE · Xavier's letter on China: 1552 CE; died that December, entry denied · Ricci arrives in China: 1583 CE · Ricci's method: Cultural accommodation, presenting as a Confucian scholar
- October 24, 1648 CEWell documented
Primary source · 2 sourceswhy?
Best source: Treaty of Westphalia
Cited as a "primary" source (no stronger domain match).The Peace of Westphalia Ends Europe's Wars of Religion
The Thirty Years' War, which began in 1618 CE as a conflict between Catholic and Protestant princes within the Holy Roman Empire before drawing in most of the great powers of Europe, ended with a set of treaties signed at Munster and Osnabruck in October 1648 CE, together known as the Peace of Westphalia. The treaties, negotiated in the name of a Christian and universal peace and a perpetual, true, and sincere amity, granted a perpetual amnesty for acts committed during the war and formally recognized the legal equality of Catholicism, Lutheranism, and the previously unrecognized Calvinism, guaranteeing adherents of the Augsburg Confession free exercise of their religion both in public churches at appointed hours and in private worship. Historians estimate the war killed between 4.5 and 8 million people, making it one of the deadliest conflicts in European history to that point.
Why it matters: Westphalia ended more than a century of intermittent religious warfare that followed the Reformation and established a framework, since called Westphalian sovereignty, in which political authority over religion rested with individual states rather than being fought over across the whole of Christendom, a shift that helped move European conflict away from confessional war and toward negotiated state interests.
How we know: The full treaty texts survive and are preserved in university and legal archives, including Yale Law School's Avalon Project, an unmediated primary record of the terms the parties actually agreed to.
War ended: Thirty Years' War (1618-1648) · Treaties signed: October 1648, Munster and Osnabruck · Faiths recognized as legally equal: Catholic, Lutheran, Calvinist · Estimated deaths: 4.5 to 8 million
Sources - 18th-20th centuriesWell documented
General source · 2 sourceswhy?
Best source: The Size and Distribution of the World's Christian Population
Cited as a "reference" source (no stronger domain match).Christianity Splinters Into Tens of Thousands of Denominations
In the centuries after the Reformation, Protestant Christianity in particular continued to divide and re-divide, producing new denominations through further theological disagreement, revival movements, missionary expansion, and migration into new regions where local leaders founded independent churches. By the early 21st century, researchers tracking global Christian affiliation counted tens of thousands of distinct Christian denominations and rites worldwide, though roughly half of the world's Protestants still belonged to one of six major historic traditions: Lutheran, Calvinist/Reformed, Anglican, Methodist, Baptist, and Pentecostal. Pew Research Center's global count found that, of all the world's Christians, about half are Catholic, more than a third Protestant, and roughly one in eight Orthodox, with the remaining fraction split among smaller groups.
Why it matters: This continual splintering shows that the Reformation did not produce one alternative to Catholicism but opened an ongoing process of division that has never really stopped, driven as much by missionary expansion into new cultures and revival movements as by the original 16th-century disputes over doctrine.
How we know: Global denominational counts come from specialized religious demography research, including the Center for the Study of Global Christianity and Pew Research Center's Global Christianity survey, both of which track church membership and affiliation data reported by denominations themselves.
Major Protestant traditions: Lutheran, Reformed, Anglican, Methodist, Baptist, Pentecostal · Share Catholic (2010 data): 50% · Share Protestant: 37% · Share Orthodox: 12%
- 1906 CEWell documented
Reputable source · 2 sourceswhy?
Best source: Pentecostalism: William Seymour
The domain "christianhistoryinstitute.org" is on our Reputable source registry.The Azusa Street Revival Launches Global Pentecostalism
William Seymour, born in Louisiana in 1870 to formerly enslaved parents, brought the Pentecostal teaching of Charles Fox Parham, that speaking in tongues was evidence of baptism in the Holy Spirit, to Los Angeles in early 1906 CE. After a month of prayer and fasting, Seymour and several companions spoke in tongues on April 9, 1906, and the growing crowds soon moved services into a former African Methodist Episcopal church building on Azusa Street, a plain structure that packed in as many as 600 people at a time for services marked by shouting, trances, and interracial worship that was unusual for its time and place. News of the revival spread through Seymour's own periodical, The Apostolic Faith, and through missionaries who carried the movement abroad; more than 200 Pentecostal missionaries, most of them women, had gone out from Azusa and related centers by 1910.
Why it matters: The Azusa Street revival is the event historians most commonly point to as the origin of the modern global Pentecostal and charismatic movement, which by the early 21st century had grown into one of Christianity's largest and fastest-growing branches, with particular strength across Africa, Latin America, and Asia.
How we know: Contemporary accounts survive in Seymour's own newspaper The Apostolic Faith, published from the revival itself between 1906 and 1908, supplemented by later historical scholarship drawing on those same primary records.
Leader: William J. Seymour · Location: 312 Azusa Street, Los Angeles · Began: April 1906 CE · Missionaries sent out by 1910: More than 200, mostly women
- November 21, 1964 CEWell documented
Primary source · 2 sourceswhy?
Best source: The Great Schism
Cited as a "primary" source (no stronger domain match).Vatican II Opens the Catholic Church to Ecumenism
The Second Vatican Council, meeting in Rome from 1962 to 1965 CE under Popes John XXIII and Paul VI, issued a decree on ecumenism, Unitatis Redintegratio, on November 21, 1964 CE, passed by a vote of 2,137 to 11 among the assembled bishops. The decree opened by stating that the restoration of unity among all Christians is one of the principal concerns of the Second Vatican Council, acknowledging that many communions now claim to be the authentic heirs of Jesus Christ and treating this division as a wound working against the church's own mission rather than as simply the fault of those outside it. The council paired this decree with Nostra Aetate, addressing the church's relationship to non-Christian religions, and both documents marked a significant shift from the Council of Trent's more confrontational posture four centuries earlier.
Why it matters: Vatican II's turn toward ecumenism reframed centuries of division, including the Great Schism of 1054 and the Reformation, as problems the Catholic Church itself had a responsibility to help heal rather than disputes settled permanently by earlier councils, and it opened decades of formal dialogue between Catholic, Orthodox, and Protestant churches that continues today.
How we know: Unitatis Redintegratio is published as an official conciliar document on the Vatican's own archive, the primary record of what the council actually decreed rather than a later summary of it.
Council: Second Vatican Council, 1962-1965 CE · Decree: Unitatis Redintegratio, promulgated November 21, 1964 · Vote: 2,137 to 11 · Paired document: Nostra Aetate (on non-Christian religions)
Sources - 20th-21st centuriesWell documented
General source · 2 sourceswhy?
Best source: Christianity Poised to Continue Its Southward March
Cited as a "reference" source (no stronger domain match).Christianity's Center Shifts to the Global South
Pew Research Center demographic projections show a Christian population that has shifted southward for at least a century and is expected to continue doing so. In 1910, Europe was home to roughly two-thirds of the world's Christians, with North America a distant second; by the early 21st century, nearly half of the world's Christians already lived in Africa and the Latin America-Caribbean region combined, driven by higher birth rates in sub-Saharan Africa and by widespread Christian disaffiliation across Western Europe. Pew's projections estimate that by 2050, sub-Saharan Africa alone will be home to nearly four in ten of the world's Christians, up from less than two percent in 1910, while Europe and North America together will hold only about a quarter of the global total.
Why it matters: This reversal means the demographic and, increasingly, theological center of a religion born in the Middle East and long associated with European institutions has moved to regions that were themselves once primarily mission fields, a shift with consequences for church leadership, doctrine, and global Christian politics that are still unfolding.
How we know: Pew Research Center's Global Christianity demographic studies draw on census data, surveys, and church membership records from around the world to build population estimates and projections across regions and time periods.
Europe's share, 1910: 66% of world's Christians · Sub-Saharan Africa's projected share, 2050: 38% · Global South share today: About 61% of world's Christians · Key driver: Higher birth rates in Africa, disaffiliation in Europe