Communion (Christian) in the context of "Chalcedonian Schism"

The Eastern Orthodox Church, officially the Orthodox Catholic Church, and also called the Greek Orthodox Church or simply the Orthodox Church, is one of the three major doctrinal and jurisdictional groups of Christianity. As of 2012, it has approximately 300 million adherents and is the third largest religious community in the world after Catholics and Sunni Muslims. The Eastern Orthodox Church operates as a communion of autocephalous churches, each governed by its bishops via local synods. The church has no central doctrinal or governmental authority analogous to the pope of the Catholic Church. Nevertheless, the Ecumenical Patriarch of Constantinople is recognised by them as primus inter pares ('first among equals'), a title held by the patriarch of Rome prior to 1054. As one of the oldest surviving religious institutions in the world, the Eastern Orthodox Church has played an especially prominent role in the history and culture of Eastern and Southeastern Europe. Since 2018, there has been an ongoing schism between Constantinople and Moscow, with the two not in full communion with each other.

Eastern Orthodox theology is based on the Scriptures and holy tradition, which incorporates the dogmatic decrees of the seven ecumenical councils, and the teaching of the Church Fathers. The church teaches that it is the one, holy, catholic and apostolic church established by Jesus Christ in his Great Commission, and that its bishops are the successors of Christ's apostles. It maintains that it practises the original Christian faith, as passed down by holy tradition. Its patriarchates, descending from the pentarchy, and other autocephalous and autonomous churches, reflect a variety of hierarchical organisation. It recognises seven major sacraments (which are called holy mysteries), of which the Eucharist is the principal one, celebrated liturgically in synaxis. The church teaches that through consecration invoked by a priest, the sacrificial bread and wine become the body and blood of Christ. The Virgin Mary is venerated in the Eastern Orthodox Church as the Theotokos, which means 'God-bearer', and she is honoured in devotions.

Full communion is a communion or relationship of full agreement among different Christian denominations or Christian individuals that share certain essential principles of Christian theology. Views vary among denominations on exactly what constitutes full communion, but typically when two or more denominations are in full communion it enables services and celebrations, such as the Eucharist, to be shared among congregants or clergy of any of them with the full approval of each.

The East–West Schism, also known as the Great Schism or the Schism of 1054, is the break of communion between the Catholic Church and the Eastern Orthodox Church since 1054. A series of ecclesiastical differences, theological disputes and geopolitical tensions between the Greek East and Latin West preceded the formal split that occurred in 1054. Prominent among these were the procession of the Holy Spirit (Filioque), whether leavened or unleavened bread should be used in the Eucharist, iconoclasm, the coronation of Charlemagne as emperor of the Romans in 800, the pope's claim to universal jurisdiction, and the place of the See of Constantinople in relation to the pentarchy.

The first action that led to a formal schism occurred in 1053 when Patriarch Michael I Cerularius of Constantinople ordered the closure of all Latin churches in Constantinople. In 1054, the papal legate sent by Leo IX travelled to Constantinople in order, among other things, to deny Cerularius the title of "ecumenical patriarch" and insist that he recognize the pope's claim to be the head of all of the churches. The main purposes of the papal legation were to seek help from the Byzantine emperor, Constantine IX Monomachos, in view of the Norman conquest of southern Italy, and to respond to Leo of Ohrid's attacks on the use of unleavened bread and other Western customs, attacks that had the support of Cerularius. The historian Axel Bayer says that the legation was sent in response to two letters, one from the emperor seeking help to organize a joint military campaign by the eastern and western empires against the Normans, and the other from Cerularius. When the leader of the legation, Cardinal Humbert of Silva Candida, O.S.B., learned that Cerularius had refused to accept the demand, he excommunicated him, and in response Cerularius excommunicated Humbert and the other legates. According to Kallistos Ware, "Even after 1054 friendly relations between East and West continued. The two parts of Christendom were not yet conscious of a great gulf of separation between them ... The dispute remained something of which ordinary Christians in East and West were largely unaware".

Western Christianity is one of two subdivisions of Christianity (Eastern Christianity being the other). Western Christianity is composed of the Latin Church and Western Protestantism, together with their offshoots such as the Old Catholic Church, Independent Catholicism and Restorationism.

The large majority of the world's 2.3 billion Christians are Western Christians (about 2 billion: 1.3 billion Latin Catholic and 1.17 billion Protestant). One major component, the Latin Church, developed under the bishop of Rome. Out of the Latin Church emerged a wide variety of independent Protestant denominations, including Lutheranism and Anglicanism, starting from the Protestant Reformation in the 16th century, as did Independent Catholicism in the 19th century. Thus, the term "Western Christianity" does not describe a single communion or religious denomination but is applied to distinguish all these denominations collectively from Eastern Christianity.

Eastern Christianity comprises Christian traditions and church families that originally developed during classical and late antiquity in the Eastern Mediterranean region or locations further east, south or north. The term does not describe a single communion or religious denomination. Eastern Christianity is a category distinguished from Western Christianity, which is composed of those Christian traditions and churches that originally developed further west.

Major Eastern Christian bodies include the Eastern Orthodox Church and the Oriental Orthodox Churches, along with those groups descended from the historic Church of the East (also called the Assyrian Church), as well as the Eastern Catholic Churches (which are in communion with Rome while maintaining Eastern liturgies), and the Eastern Protestant churches. Most Eastern churches do not normally refer to themselves as "Eastern", with the exception of the Assyrian Church of the East and its offshoot, the Ancient Church of the East.

The Ethiopian Orthodox Tewahedo Church (Amharic: የኢትዮጵያ ኦርቶዶክስ ተዋሕዶ ቤተ ክርስቲያን, romanized: Yä-ityopp'ya ortodoks täwahədo betä krəstiyan) is the largest of the Oriental Orthodox Churches. One of the few Christian churches in Africa originating before European colonization of the continent, the Ethiopian Orthodox Tewahedo Church dates back to the Christianization of the Kingdom of Aksum in 330, and has between 38 million and 46 million adherents in Ethiopia. The Ethiopian Orthodox Tewahedo Church claims 60 million members worldwide. It is a founding member of the World Council of Churches. The Ethiopian Orthodox Tewahedo Church is in communion with the other Oriental Orthodox churches (the Eritrean Orthodox Tewahedo Church, the Coptic Orthodox Church of Alexandria, the Malankara Orthodox Syrian Church, the Armenian Apostolic Church, and the Syriac Orthodox Church).

The Ethiopian Orthodox Tewahedo Church had been administratively part of the Coptic Orthodox Church of Alexandria from the first half of the 4th century until 1959, when it was granted autocephaly with its own patriarch by Pope Cyril VI of Alexandria, Pope of the Coptic Orthodox Church.

In the year before the First Council of Constantinople in 381, Nicene Christianity became the official religion of the Roman Empire when Theodosius I, emperor of the East, Gratian, emperor of the West, and Gratian's junior co-ruler Valentinian II issued the Edict of Thessalonica in 380, which recognized the catholic orthodoxy, as defined by the Council of Nicea, as the Roman Empire's state religion. Historians refer to this state-sponsored church using a variety of terms: the catholic church, the orthodox church, the imperial church, the Roman church, or the Byzantine church, with some also used for wider communions extending beyond the Roman Empire. The Eastern Orthodox Church, Oriental Orthodoxy, and the Catholic Church all claim to stand in continuity from the Nicene Christian church to which Theodosius granted recognition. Political differences between the Eastern Roman Empire and the Persian Sassanid Empire led to the separation of the Church of the East in 424. A doctrinal split within the imperial church led to the independence of early Oriental Orthodoxy, while the fall of the Western Roman Empire initiated the gradual separation between Eastern and Western Christianity, culminating in the East-West schism of 1054. The Western Church evolved into the Latin Catholic Church while the Eastern Church that remained under the patronage of the Eastern empire and evolved into the Greek Orthodox Church.

Earlier in the 4th century, following the Diocletianic Persecution of 303–313 and the Donatist controversy that arose in consequence, Constantine the Great had convened councils of bishops to define the orthodoxy of the Christian faith and to expand on earlier Christian councils. A series of ecumenical councils convened by successive Roman emperors met during the 4th and the 5th centuries, but Christianity continued to suffer rifts and schisms surrounding the theological and christological doctrines of Arianism, Nestorianism, Miaphysitism, and Dyophysitism. In the 5th century, the Western Roman Empire decayed as a polity; invaders sacked Rome in 410 and in 455, and Odoacer, an Arian barbarian warlord, forced Romulus Augustus, the last nominal Western Emperor, to abdicate in 476. However, apart from the aforementioned schisms, the church as an institution persisted in communion, if not without tension, between the East and West. In the 6th century, the Byzantine armies of the Byzantine Emperor Justinian I recovered Italy and other regions of the Western Mediterranean shore. The Byzantine Empire soon lost most of these gains, but it held Rome, as part of the Exarchate of Ravenna, until 751, a period known in church history as the Byzantine Papacy. The early Muslim conquests of the 7th–9th centuries would begin a process of converting most of the then-Christian world in the Levant, Middle East, North Africa, regions of Southern Italy and the Iberian Peninsula to Islam, severely restricting the reach both of the Byzantine Empire and of its church. Christian missionary activity directed from the capital of Constantinople did not lead to a lasting expansion of the formal link between the church and the Byzantine emperor, since areas outside the Byzantine Empire's political and military control set up their own distinct churches, as in the case of Bulgaria in 919.