Organization of the Eastern Orthodox Church

The Eastern Orthodox Church, officially the Orthodox Catholic Church and commonly known simply as the Orthodox Church is a communion composed of up to seventeen separate autocephalous (self-governing) hierarchical churches that profess Eastern Orthodoxy and recognise each other as canonical (regular) Eastern Orthodox Christian churches.
Each constituent church is self-governing; its highest-ranking bishop called the primate (a patriarch, a metropolitan or an archbishop) reports to no higher authority. Each regional church is composed of constituent eparchies (or dioceses) ruled by bishops. Some autocephalous churches have given an eparchy or group of eparchies with varying degrees of autonomy (meaning they have limited self-government). Such autonomous churches maintain varying levels of dependence on their mother church, usually defined in a tomos or another document of autonomy. In many cases, autonomous churches are almost completely self-governing, with the mother church retaining only the right to appoint the highest-ranking bishop (often an archbishop or metropolitan) of the autonomous church.
Normal governance is enacted through a synod of bishops within each church.
The Eastern Orthodox Church is decentralised, having no central authority, earthly head or a single bishop in a leadership role. Thus, the Eastern Orthodox use a synodical system canonically, which is significantly different from the hierarchical organisation of the Catholic Church that follows the doctrine of papal supremacy. References to the Ecumenical Patriarch of Constantinople as a sole authoritative leader are an erroneous interpretation of his title “first among equals". His title is of honor rather than authority and in fact the Ecumenical Patriarch has no direct authority over churches other than the Constantinopolitan Church. The Ecumenical Patriarch's unique role is sometimes referred to as being the "spiritual leader" of the Eastern Orthodox Church, although even this is disputed.
The autocephalous churches are normally in full communion with each other, so any priest of any of those churches may lawfully minister to any member of any of them, and no member of any is excluded from any form of worship in any of the others, including the reception of the Eucharist. However, there have been varying instances in the history of the Eastern Orthodox Church where communion has been broken between member churches for short periods, particularly over autocephaly issues or disagreements over ecumenism with other Christian denominations.
Following Justinian, the church existed only as a single denomination of five communing churches ruled by five patriarchs: the bishops of Rome, Constantinople, Alexandria, Antioch, and Jerusalem, collectively referred to as the Pentarchy. Each of the five patriarchs had jurisdiction over bishops in a specified geographic region which did not overlap with the jurisdiction of another patriarch. This continued until 927, when the Bulgarian Patriarchate became the first newly promoted patriarchate to join the original five.
Historically, the Patriarch of Rome was considered to be the "first in place of honor" among the five patriarchs. Disagreement about the limits of his authority was one of the causes of the Great Schism, conventionally dated to the year 1054, which split the previously unified Church into the Roman Catholic Church in the West, headed by the Pope, and the Orthodox Catholic Church (more commonly known today as the Eastern Orthodox Church), led by the four eastern patriarchs. After the schism, the honorary primacy of the Bishop of Rome shifted to the Patriarch of Constantinople, who had previously been accorded second-place rank at the First Council of Constantinople.
In the 5th century, Oriental Orthodoxy separated from Chalcedonian Christianity (and is therefore separate from both the Eastern Orthodox Church and Roman Catholic Church), well before the 11th century Great Schism. It should not be confused with Eastern Orthodoxy or Roman Catholicism.
Ranked in order of seniority, with the year of independence (autocephaly) given in parentheses, where applicable. There are a total of 17 autocephalous Eastern Orthodox churches which are recognized to various degrees among the communion of the Eastern Orthodox Church.
Canonicity refers to the state of being in communion with the larger Eastern Orthodox Church (making the church in question undisputedly a constituent of the Eastern Orthodox Church), whereas autocephaly refers to the state of being more or less self-governing. Canonicity is binary (two churches are either in communion or not) while autocephaly exists on a spectrum. Disputes over autocephaly often lead to short-term breaks in communion for political reasons. These short-term breaks are typically not due to differences in doctrine or theology.
The four ancient Eastern Orthodox Patriarchates, along with the See of Rome, formed the historical Pentarchy, and remained in communion with each other after the East-West Schism in 1054. The concept of the Pentarchy and the title of "Patriarch" itself, as opposed to Archbishop or Exarch, is attributed to St Justinian in AD 531.
Note:
Note:
The typical order that the four ancient churches appear in the diptychs is the same order given above. While every major church places the four ancient churches in their diptychs before the other autocephalous churches, this order may still differ slightly. For example, in the diptychs of the Russian Orthodox Church and some of its daughter churches (e.g., the Orthodox Church in America), the ranking of the five junior patriarchates is: Russia, Georgia, Serbia, Romania, Bulgaria. The ranking of the archbishoprics is the same, with the Church of Cyprus being the only ancient one (AD 431).
The following churches recognize all other mainstream Eastern Orthodox churches, but are not recognised by any of them due to various disputes:
True Orthodox Christians are groups of traditionalist Eastern Orthodox churches which have severed communion since the 1920s with the mainstream Eastern Orthodox churches for various reasons, such as calendar reform, the involvement of mainstream Eastern Orthodox in ecumenism, or the refusal to submit to the authority of mainstream Eastern Orthodox Church. The True Orthodox Church in the Soviet Union was also called the Catacomb Church; the True Orthodox in Romania, Bulgaria, Greece and Cyprus are also called Old Calendarists.
These groups refrain from concelebration of the Divine Liturgy with the mainstream Eastern Orthodox, while maintaining that they remain fully within the canonical boundaries of the Church: i.e., professing Eastern Orthodox belief, retaining legitimate apostolic succession, and existing in communities with historical continuity. However, their existence outside of communion with the other churches makes the True Orthodox automatically outside of the Eastern Orthodox Church.
The churches which follow True Orthodoxy are:
Old Believers are divided into various churches which recognize neither each other nor the mainstream Eastern Orthodox Church.
The following churches use the term "Orthodox" in their name and carry belief or the traditions of Eastern Orthodox church, but blend beliefs and traditions from other denominations outside of Eastern Orthodoxy: