Great Eastern Schism

the division of the Christian church into Catholic and Eastern Orthodox.

The principal cause of the Great Eastern Schism was the struggle for supremacy in the church between the Roman popes and the patriarchs of Constantinople. The schism was also furthered by the differences that had become clearly evident by the seventh century between the Eastern and Western churches in dogma, organization, and ritual. The grounds for the schism were laid by the rift around 867 between Pope Nicholas I and Patriarch of Constantinople Photius. There was dissension primarily because both claimed to be head of the church in Bulgaria, and, in the matter of dogma, because of the addition to the Creed of the word filioque. By the early tenth century the break had been healed.

The second stage of the schism was linked with the conflict between Patriarch of Constantinople Cerularius and the Curia Romana, which claimed that the clergy of southern Italy in the Byzantine possessions that had been captured by the Normans should be subordinate to the papacy. On July 16, 1054, the Roman legate, Cardinal Humbert, anathematized Cerularius, and on July 20, Cerularius did the same to Humbert. (Traditionally, therefore, the schism is dated from 1054.) The final break occurred after the capture of Constantinople by the Crusaders in 1204. Attempts at reuniting the Catholic and Orthodox churches from the 13th through 15th centuries proved unsuccessful.