The schism began when a church synod deposed the Ecumenical Patriarch of Constantinople Arsenios Autoreianos on the initiative of Emperor Michael VIII Palaiologos.
[2] During the following centuries, the western Church adopted practices, such as the use of unleavened bread in the Eucharist and fasting on Saturday, that remained alien to eastern Christians.
[3] The westen concept known as filioque ('and from the Son') was officially introduced in Rome early in the 11th century, demonstrating the papacy's claim to supreme authority.
[5] During the Fourth Crusade in 1204–1205, a coalition of western knights and Venetian merchants captured Constantinople, and seized large chunks of the Byzantine Empire.
[6] With his active support, the Eastern Orthodox clergy of Constantinople elected Michael IV Autoreianos (d. 1212) as the new Ecumenical Patriarch in 1208.