Cardinal Humbert Excommunicates the Patriarch and Splits the Church
A furious papal legate lays a bull of excommunication on the altar of Hagia Sophia
Quick facts
- Papal legate
- Cardinal Humbert of Silva Candida
- Patriarch
- Michael Cerularius
- Date
- July 16, 1054 CE
- Anathemas lifted
- 1965, by Pope Paul VI and Patriarch Athenagoras I
What happened
Long-simmering theological and political tensions between the Latin west and Greek east, over questions like the filioque clause in the Nicene Creed and the use of unleavened bread in the Eucharist, came to a head after Norman conquests in southern Italy suppressed Greek church practices there. Patriarch Michael Cerularius of Constantinople retaliated by pressuring Latin churches in his city to adopt Greek customs. Pope Leo IX sent a delegation led by Cardinal Humbert of Silva Candida, who received a cold reception and, after Cerularius refused to deal with him further, walked into Hagia Sophia during a service on July 16, 1054 CE and placed a bull of excommunication against the patriarch on the altar. Cerularius responded in kind, excommunicating Humbert and his fellow legates.
Why it matters
Although modern scholars agree no single event caused the split and relations between individual eastern and western churches stayed workable for some time afterward, this mutual excommunication became the symbolic starting point historians call the Great Schism, and the rift deepened further after the sack of Constantinople by western crusaders in 1204 CE.
How we know
The Orthodox Church in America's official history of the schism narrates the sequence of events leading to July 1054 CE and the mutual excommunications, drawing on the historical record of the legation and Cerularius's response.
Sources
- Orthodox Church in America. The Great Schism · Primary source (author-declared)oca.org · Cited as a "primary" source (no stronger domain match). · Link is live and its text matches the event's key terms (Jul 2026)
- Christian History Institute (George T. Dennis). 1054 The East-West Schism · Reputable sourcechristianhistoryinstitute.org · The domain "christianhistoryinstitute.org" is on our Reputable source registry. · Link is live and its text matches the event's key terms (Jul 2026)
See something wrong? . Corrections with a source get fixed fastest.
Part of a timelineThe Byzantine Empire27 events · How the eastern half of Rome outlived the west by a thousand years, then fell to Ottoman cannonView all →