The Orthodox Church, officially the Orthodox Catholic Church, is a Christian church. Their type of Christianity is also called Orthodox Christianity or Orthodoxy. Their members are called Orthodox Christians, although there is another group of Churches called Oriental Orthodox that is not in communion with the Orthodox Church. There are about 300 million Orthodox Christians in the world. Most Orthodox Christians are found in Russia, Greece, Eastern Europe, and the Middle East, but there are Orthodox Christians everywhere in the world.
In 395, the Roman Empire was split into a western part, and an eastern part. The western part lasted to the 5th or 6th century, the exact dates are a point of debate. The eastern part, which is commonly called Byzantine Empire, lasted until the 15th century. The split of the Roman Empire also affected the church, which developed differently in both parts. In 1054, there was the East–West Schism. The western part developed what is now the Roman-Catholic Church, the eastern part is now called Eastern Orthodox Church. In the west, there is the patriarch of Rome, who is commonly called the Pope. In the east, there is the patriarch of Constantinople. Because of historical developments, many Eastern Orthodox churches also have a local patriarch. In the west, the pope is an absolute leader. The patriarch of Constantinople is the "first among equals", his power is not absolute.
Distribution of Eastern Orthodoxy in the world by country
The many churches of the Orthodox Church are distinct in terms of administration and local culture, but for the most part exist in full communion with one another. Most of these churches are led by patriarchs. Most patriarchs recognise the Patriarch of Constantinople as their spiritual leader.
The following listing contains a selection of Eastern Orthodox Churches. Unless otherwise stated, they are in communion:
In the 17th century a group of people split from the Eastern Orthodox Church, because they did not agree with some changes that were introduced. These people are known as Old Believers today. There are two big groups of Old Believers, and a few smaller ones. Old Believers are not in communion with the other Eastern Orthodox Churches.