Orthodox Churches (those that use the word "Orthodox" in the name) belong mainly to two groups, Eastern Orthodoxy and Oriental Orthodoxy. Apart from these two groups, some other quite unconnected Churches in the West also call themselves Orthodox. An example is the Celtic Orthodox Church.
Eastern Orthodox and Oriental Orthodox
The division between these two families of Churches occurred in 451 over the definition by the Council of Chalcedon that Jesus exists "in two natures", one human and one divine, and that "both natures concur in one person and in one reality [hypostasis]. They are not divided or cut into two persons, but are together the one and only and only-begotten Word, God, the Lord Jesus Christ." The Council thus declared that Christ is one person in two natures "of one substance with the Father according to his divinity, of one substance with us according to his humanity ... in two natures without confusion, without change, without division, without separation."
The Churches that accept the Council's definition are known as Chalcedonian Churches, and those that reject it as non-Chalcedonian or pre-Chalcedonian. The Chalcedonian Churches in the East are known collectively as the Eastern Orthodox Church. (The Roman Catholic Church in the West is also a Chalcedonian Church, since it accepts that Council's definition, which was largely based on a document of Pope Leo I.) Those that reject the Council form what is known as Oriental Orthodoxy.
Dialogues aimed at achieving full communion between the Eastern and the Oriental Orthodox are in progress, with the hope of overcoming the schism that still divides them. These dialogues have led to a large measure of agreement, but not yet to full normal communion.
Apart from the use by the few parishes of Western Rite Orthodoxy of adapted or specially composed liturgies based on Latin liturgical rites, all the Churches that form the Eastern Orthodox Church use the Byzantine Rite liturgy, celebrating it in different languages. The Oriental Orthodox Churches, on the contrary, use a great variety of liturgies.
Some Churches of the Eastern Orthodox tradition are not in communion with the general body, usually because of disputes about the use of the Julian calendar, but in some cases because of political problems. There is one such case also in Oriental Orthodoxy, namely that of the Malabar Independent Syrian Church, in India.
- Eastern Orthodox Churches (in full communion)
- Orthodox Church of Constantinople
- Greek Orthodox Church of Alexandria
- Greek Orthodox Church of Antioch
- Orthodox Church of Jerusalem
- Russian Orthodox Church
- Serbian Orthodox Church
- Romanian Orthodox Church
- Bulgarian Orthodox Church
- Georgian Orthodox Church
- Cypriot Orthodox Church
- Orthodox Church of Greece
- Polish Orthodox Church
- Albanian Orthodox Church
- Czech and Slovak Orthodox Church
- Orthodox Church in America
- Ukrainian Autocephalous Orthodox Church - Canonical
- Eastern Orthodox Churches (not in communion)
- Greek Old Calendarists Matthewites
- Greek Old Calendarists Florinites
- Orthodox Church of Greece (Holy Synod in Resistance)
- Old Calendar Romanian Orthodox Church
- Old Calendar Bulgarian Orthodox Church
- Russian Orthodox Old-Rite Church
- Lipovan Orthodox Old-Rite Church
- Russian Old-Orthodox Church
- Pomorian Old-Orthodox Church
- Belarusian Autocephalous Orthodox Church
- Bulgarian Orthodox Church - Alternative synod
- Holy Orthodox Church in North America
- Macedonian Orthodox Church
- Montenegrin Orthodox Church
- Orthodox Church in Italy
- Russian Orthodox Church in America
- Russian True Orthodox Church
- Autocephalous Turkish Orthodox Patriarchate
- Ukrainian Orthodox Church - Kiev Patriarchate
- Ukrainian Autocephalous Orthodox Church
- Oriental Orthodox Churches (in full communion)
- Coptic Orthodox Church of Alexandria
- Syriac Orthodox Church of Antioch
- Armenian Orthodox Church
- Indian (Malankara) Orthodox Church
- Ethiopian Orthodox Church
- Eritrean Orthodox Church
- Oriental Orthodox Church (not in communion)
Some small churches in the West use the word "Orthodox" in their titles but are quite distinct from these two families of churches. Examples are the Celtic Orthodox Church and those mentioned in this account.
- List of Christian denominations
- List of Christian denominations by number of members
- "The Oriental Orthodox churches, along with those of the Byzantine tradition or Eastern Orthodox, belong to the larger family of the Orthodox churches. The two groups are not in communion with each other" (Orthodox churches (Oriental)
- Definition concerning the two natures of Christ
- J. Martin Bailey. Who are the Christians in the Middle East? (Eerdmans 2003), p. 66
- James Leslie Houlden, Jesus in History, Thought and Culture: An Encyclopedia, volume 1, p. 666
- Ronald G. Roberson, The Eastern Christian Churches: a brief survey, p. 5
- Thomas E. Fitzgerald, The Ecumenical Movement: An Introductory History, p. 56]
- Pastoral Agreement between the Coptic Orthodox and Greek Orthodox Patriarchates of Alexandria (2001)
- Frequently Asked Questions About the Oriental Orthodox
- The Coptic Orthodox Church
- Growth in Agreement II, by Jeffrey Gros, Harding Meyer, William G. Rusch (Eerdmans Publishing, 2000 ISBN 9782825413296) chapter VIII: Eastern Orthodox-Oriental Orthodox Dialogue
- Texts of the Agreed Statements of the Joint Commission
- "The Orthodox all the world over must follow the Rite of Constantinople. In this unjustifiable centralization we have a defiance of the old principle, since Antioch, Jerusalem, Alexandria, Cyprus, in no way belong to the Byzantine Patriarchate" (Adrian Fortescue, Rites).
- "There are three Ethiopic liturgies all addressed to the Son. In Syria itself the Monophysite Second Liturgy of S. Peter ... (is) directed to the Son, as is part of the eucharistic prayer of the Syriac St James itself, which is followed in this by nearly all the sixty or seventy lesser Syriac liturgies" (The Shape of the Liturgy, by Gregory Dix, published by Continuum, 2005, page 180). The Coptic Church uses the Liturgy of St Cyril, the Liturgy of St Gregory the Theologian, and the Coptic Liturgy of St Basil. In Ethiopia, the most commonly used liturgy is the Ethiopian Orthodox Liturgy of the Apostles.
- John Binns: An Introduction to the Christian Orthodox Churches (Cambridge University Press, 2005 ISBN 9780521667388)
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