The Great Schism of 1054: How East and West Split Apart

On July 16, 1054, a delegation from Pope Leo IX, led by Cardinal Humbert of Silva Candida, walked into the Hagia Sophia in Constantinople during a liturgy and placed a papal bull of excommunication on the high altar, targeting Patriarch Michael Cerularius. Days later, Cerularius responded in kind, excommunicating the papal legates. This dramatic exchange is traditionally remembered as the moment of the Great Schism — the definitive split between the Latin Church of the West and the Greek-speaking Orthodox Church of the East.

A Divide Centuries in the Making

The events of 1054 were less a sudden break than the visible culmination of a rift that had been widening for centuries. Rome and Constantinople had grown apart linguistically, culturally, and politically ever since the empire itself split into Western and Eastern halves. By the time of the schism, the two churches disagreed on a number of significant matters.

The Filioque Controversy

Perhaps the most contentious theological issue was the filioque clause — a Latin phrase meaning “and the Son” that the Western Church had added to the Nicene Creed, stating that the Holy Spirit proceeds from the Father “and the Son,” rather than from the Father alone. Eastern theologians viewed this as both a theological error and an illegitimate unilateral change to an ecumenical creed that no single church had the authority to alter.

Authority, Liturgy, and Culture

Beyond the filioque, the churches clashed over the scope of papal authority. Rome increasingly claimed universal jurisdiction over all Christendom, a claim the East rejected, holding instead that authority rested collectively with the ancient patriarchates and ecumenical councils. Liturgical differences — such as the Western use of unleavened bread in the Eucharist versus the Eastern use of leavened bread — became flashpoints as well, alongside disputes over clerical celibacy and the proper date of Easter.

Mutual Excommunication, Not Immediate Rupture

Contemporaries did not necessarily view the events of 1054 as a permanent, irrevocable split; the mutual excommunications technically applied only to the individuals involved, not to the churches as a whole. But the rift deepened over the following centuries, especially after the catastrophic Fourth Crusade in 1204, when Latin crusaders sacked Constantinople itself, an act of violence against fellow Christians that Orthodox Christians have never forgotten.

A Wound Still Being Addressed

The mutual excommunications of 1054 were formally lifted only in 1965, when Pope Paul VI and Ecumenical Patriarch Athenagoras I issued a joint declaration expressing regret and removing them from memory, as part of the ecumenical spirit encouraged by the Second Vatican Council. Full communion between Rome and Constantinople, however, has never been restored, and the Great Schism remains the deepest and longest-standing division in Christian history.