The East-West Schism, usually called the Great Schism, was the event that separated Eastern Orthodoxy and Western Catholicism in 1054. The two churches split along doctrinal, theological, linguistic, political, and geographic lines; they remain unreconciled to this day.
With movement of the emperor and political authority from Rome to Constantinople, a division was caused in the religious climate of the empire. Because of the custom of the emperor having more or less authority in both temporal and religious matters, this eventually caused a split between Bishops following the Pope in Rome and those following the emperor in Constantinople.
The catalysts of the first schism included:
- the insertion of the filioque clause into the Nicene Creed
- the use of unleavened bread in the West vs. leavened bread in the East for the Eucharist
- disputes in the Balkans over whether the Western or Eastern church had jurisdiction
- the designation of the Patriarch of Constantinople as ecumenical patriarch (which was understood by Rome as universal patriarch and therefore disputed)
- disputes over whether the Patriarch of Rome (the Pope) should be considered a higher authority than the other Patriarchs (all five Patriarchs of the One Holy Catholic and Apostolic Church agreed that the Patriarch of Rome should receive higher honors than the other four; they disagreed about whether he had authority over the other four).
- the concept of Ceasaropapism, a tying together in some way of the ultimate political and religious authorities, which were physically separated much earlier when the capital of the empire was moved from Rome to Constaninople. There is controversy over just how much this so-called "ceasaropapism" actually existed and how much was a fanciful invention, centuries later, by western European historians.
- the much more diverse and changing liturgical practices in the west compared to the more uniform and fixed practices in the east.
This lead to the exchange of excommunications by the representative of Pope Leo IX and the Patriarch of Constantinople Michael Cerularius in 1054 (finally rescinded in 1965) and the separation of the Roman Catholic and the Orthodox churches, each of which now claims to be "the One Holy Catholic and Apostolic Church." Though communion was not finally broken until after the Ottoman invasion of Constantinople in 1453 the fundamental breach has never been healed.