The Eastern churches
Separated from the West, the Orthodox churches of the East have developed their own way for half of Christian history. Each national church is autonomous. The “ecumenical patriarch” of Constantinople is not the Eastern pope but merely the first in honour among equals in jurisdiction. Eastern Orthodoxy interprets the primacy of Peter and therefore that of the pope similarly, denying the right of the pope to speak and act for the entire church by himself, without a church council and without his episcopal colleagues. Because of this polity Eastern Orthodoxy has identified itself more intimately with national cultures and with national regimes than has Roman Catholicism. Therefore the history of church–state relations in the East has been very different from the Western development, because the church in the East has sometimes tended toward the extreme of becoming a mere instrument of national policy while the church in the West has sometimes tended toward the extreme of attempting to dominate the state. The history of ecumenical relations between Eastern Orthodoxy and Protestantism during the 20th century was also different from the history of Protestant–Roman Catholic relations. While keeping alive their prayer for an eventual healing of the schism with the Latin Church, some of the Orthodox churches have established communion with Anglicanism and with the Old Catholic Church and have participated in the conferences and organizations of the World Council of Churches.
Doctrinal authority for Eastern Orthodoxy resides in the Scriptures, the ancient creeds, the decrees of the first seven ecumenical councils, and the tradition of the church. In addition to the issues mentioned in the discussion of Roman Catholicism above, the chief dogmatic difference between Roman Catholic and Eastern Orthodox thought is on the question of the procession of the Holy Spirit from the Father and from the Son, or the Filioque.
But “orthodoxy,” in the Eastern use of the term, means primarily not a species of doctrine but a species of worship. The Feast of Orthodoxy on the first Sunday of Lent celebrates the end of the iconoclastic controversies and the restoration to the churches of the icons, which are basic to Orthodox piety. In Orthodox churches (as well as in those Eastern churches that have reestablished communion with Rome), the most obvious points of divergence from general Western practice are the Byzantine liturgy, the right of the clergy to marry before ordination, though bishops may not be married, and the administration to the laity of both bread and wine in the Eucharist at the same time by the method of intinction.