Which major religious split in 1054 divided the Byzantine and Latin churches?

The major religious split associated with 1054 was the East–West Schism, which separated the Catholic Church in the Latin West from the Eastern Orthodox Church.

The event was not caused by one disagreement alone. Centuries of political rivalry, cultural difference, and theological disputes strained relations between Rome and Constantinople. Key issues included papal claims to universal authority, the use of the Filioque clause concerning the procession of the Holy Spirit, and differences in liturgical practice, including the type of bread used in the Eucharist.

In July 1054, papal legates led by Cardinal Humbert placed a bull of excommunication on the altar of Hagia Sophia. Patriarch Michael I Cerularius responded by excommunicating the legates. These actions became the conventional date of the schism, although the separation developed gradually and was reinforced by later events, especially the Fourth Crusade's sack of Constantinople in 1204.

The split was not immediately understood as a permanent division by everyone alive in 1054. Temporary attempts at reconciliation continued, but the Catholic and Eastern Orthodox churches remain distinct traditions.