A family of Churches, mostly situated mainly in E. Europe; each Church is independent in its internal administration, but all share the same faith and are in communion with each other, acknowledging the honorary primacy of the Patr. of Constantinople (or Oecumenical Patriarch).
What is known as ‘the Orthodox Church’ developed historically from the Church of the Byzantine Empire. It became limited on its E. side by the Monophysite and Nestorian schisms of the 5th–6th cents. (The Oriental Orthodox Churches also claim the title ‘Orthodox’.) From the 9th cent. there was increasing tension between Rome and Constantinople, leading to the final breach which is conventionally dated in 1054; it was in fact a gradual process. The main doctrinal points at issue were the Papal claims and the Filioque. Bounded on the E. and W., the Orthodox Church expanded to the North. A missionary advance was inaugurated in the 9th cent. by Sts Cyril and Methodius. Bulgaria, Serbia, and subsequently Russia were converted to the Christian faith largely through the efforts of Byzantine missionaries. Since the fall of Constantinople to the Turks (1453), the Church of Russia has been the largest and most influential member of the Orthodox communion. For over five centuries Orthodoxy suffered persecution, first under the Ottoman Empire and then under Communism, but with the collapse of the Communist power c.1988, a new era of expansion began in Russia and the rest of E. Europe. Largely through immigration after 1920, Orthodoxy has been taken to the United States of America, W. Europe, Australia, and Africa.
The faith of the Orthodox Church is based primarily on the dogmatic definitions of the seven Oecumenical Councils. Certain local Councils have also exercised a decisive influence on Orthodox doctrine, especially those of Constantinople in 1341 and 1351, which endorsed the teaching of Hesychasm concerning the Divine light; and the Councils of Jassy (1642) and Jerusalem (1672), which clarified Orthodox teaching on the Eucharist and the nature of Church. Orthodox acknowledge the seven sacraments, or ‘mysteries’ as they are termed, though no rigid distinction is drawn between them and other sacramental actions such as burial of the dead. Baptism is by immersion; chrismation (confirmation) is administered by the priest immediately after Baptism, and children are taken to Communion from infancy. In principle services are in the language of the people, but in many places an archaic form is used. The veneration of icons plays an important part in Orthodox worship, both private and public. Intercession for the departed is emphasized in Orthodox spirituality, but the doctrine of purgatory, as developed in RCism, is not accepted. Monasteries have been influential throughout Orthodox history; the chief monastic centre is Mount Athos. Bishops are drawn from the celibate clergy; parish priests are generally married, but must be so before becoming deacons. Most Orthodox Churches are now represented on the World Council of Churches; in recent years they have begun to develop friendly links with the Oriental Orthodox Churches.