Constantine legalizes the religion Rome had been killing people for
What happened
After a vision he reported experiencing before the Battle of the Milvian Bridge in 312 CE, the emperor Constantine converted to Christianity, a faith the Roman state had periodically persecuted for nearly three centuries. In February 313 CE he summoned his co-emperor Licinius to Milan, and together they issued what is known as the Edict of Milan, granting Christians throughout the empire the legal right to organize churches and worship openly, and ordering the return of property confiscated from them during earlier persecutions. The edict did not make Christianity Rome's official religion, only legal; that step would not come until the Edict of Thessalonica, decades later in 380 CE.
Why it matters
A religion whose adherents Rome had executed for refusing to sacrifice to the emperor was now protected by that same imperial office, a reversal with no precedent in Roman history. Within a lifetime, the empire that once fed Christians to the arena would be actively building the church into its own institutional structure, reshaping European religious and political life for the next fifteen centuries.
How we know
The Edict of Milan's terms survive quoted in the works of contemporary Christian writers, and Constantine's own later reign, openly favoring Christian institutions and convening church councils, corroborates the sincerity of the shift the edict describes rather than a purely tactical gesture.
Sources
- World History Encyclopedia. Constantine's Conversion to Christianity · Reputable sourceworldhistory.org · The domain "worldhistory.org" is on our Reputable source registry. · Link is live and its text matches the event's key terms (Jul 2026)
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