Eastern Orthodox Church
The Eastern Orthodox Church is one of the major branches of Christianity and comprises a number of Churches in Greece, Eastern Europe, Russia, Asia Minor, and the Middle East. Each of these Churches - the best-known are the Greek Orthodox Church and the Russian Orthodox Church - is autonomous and covers a distinct geographical area (usually a nation-state), but they are all committed to similar religious doctrines and acknowledge the primacy of the patriarch of Constantinople. The Eastern Orthodox Church may be contrasted, in one dimension, with Western Christianity (i.e., Roman Catholicism and the various Protestant denominations which came into existence during and after the Reformation) - see further below - and, in another dimension, with the various Churches of the Middle East and neigbouring regions (e.g., the Coptic Church and the Armenian Church) which differ on certain points of doctrine from the Eastern Orthodox Church and, rather confusingly, are said to constitute the Oriental Orthodox Church. (The Eastern Orthodox Church is also known as the Orthodox Catholic Church, the Orthodox Church, the Byzantine Church, and the Greek Orthodox Church.)
The Eastern Orthodox Church came into existence in the eleventh century as a result of the Great (East-West) Schism, which entrenched already existing differences within the Christian Church. The Roman emperor Diocletian (reigned 284-305) divided the Roman Empire for administrative purposes into two halves: a Latin-speaking western half with Rome as its capital, and a Greek-speaking eastern half with Constantinople as its capital. The Christian Church, especially after [[Christian]ity became the official religion of the Roman Empire, tended in its organisation and in other ways to reflect these differences, the Western Church using Latin in its services and recognising the primacy of the bishop of Rome (the Pope), and the Eastern Church using Greek in its services and recognising the primacy of the Patriarch (i.e., the bishop) of Constantinople. Over the centuries there were disagreements between the Pope in Rome and the Patriarch of Constantinople, and in 1054 doctrinal differences and a dispute about the extent of papal authority led to a formal break and mutual excommunication between the Eastern Church and the Western Church. It was this break, usually referred to as the Great Schism or Great East-West Schism, which brought into existence the Roman Catholic Church in the western half of the Roman Empire and the Eastern Orthodox Church in the eastern half.
Like the various denominations of Western Christianity, the Eastern Orthodox Church recognises the Bible, i.e., the Old and New Testaments, as its primary source of religious truth. However, in the case of the Old Testament it uses the Greek Septuagint and accepts as canonical an additional ten books - the so called ’αναγιγνωσκόμενα (anagignoskomena, the (books) that are read) - which are not contained in the 39-book Old Testament recognised by most western Christian denominations. In interpreting the Bible the Eastern Orthodox Church, like the Roman Catholic Church but unlike many Protestant Churches, gives some weight to the traditions of the Church.
In many respects the doctrines of the Eastern Orthodox Church are similar to those of most of the denominations of Western Christianity. Thus both branches of Christianity accept the doctrine of the Trinity (i.e., the belief that God the Father, God the Son, and God the Holy Spirit, are three 'persons' but one substance) and the belief that Jesus, as the Son of God who lived on earth as a human being, has two natures and is both fully divine and fully human. However, the Eastern Orthodox Church has a relatively benign view of human nature, at least by comparison with the view advanced by St. Augustine and endorsed by some Protestant denominations: it accepts that as a result of the 'Fall of Man', i.e., the sin of the first man Adam, humanity has inherited a tendency to sin, but denies that human nature is, as e.g., Calvin maintained, utterly 'depraved and corrupt'. It also denies that mankind collectively shares in Adam's guilt, and partly in consequence of this, offers an account of human salvation which differs strikingly from that taught by some Protestant denominations: it does not interpret Jesus' crucifixion as an instance of 'punitive substitution', i.e., it does not hold that Jesus was an innocent victim who was punished by God as a substitute for the sins of humankind, but rather it sees Jesus' death, descent into hell, and resurrection as effecting a change in human nature, rescuing humanity from a future apart from God, and making it possible for human beings to approach closer to God. For the Eastern Orthodox Church salvation lies not simply in belief in Jesus but in a life in which we become more like God - a process known as θέωσις (theosis).
A distinctive feature of devotion in the Eastern Orthodox Church is the use of icons, i.e., representations of Jesus or one of the saints usually painted on wood in a traditional Byzantine style. Icons are to be found not only in Eastern Orthodox churches but in the homes of members of Church. The icon is not itself venerated, but is nonetheless felt to share in some way in the sanctity of the person it represents. (The English word 'icon' is a transliteration of the Greek word εικών (eikon, likeness or image).)