The Oriental Orthodox Church (Oriental Orthodoxy) is collectively made up of the Armenian, Coptic, Ethiopian, Eritrean, Syriac and Indian Orthodox Churches. Some of these churches are considered to be heirs to some of the most ancient traditions in the Christian world and is estimated to have 50 million members worldwide. Each of the six churches can trace its lineage back to the origins of the first Christian Church set up by the apostolic missions in the 1st century.

1. Armenian - Saint Thaddeus and Bartholomew were martyred in Armenia.
2. Coptic - Saint Mark is considered to be the first bishop of Alexandria.
3. Ethiopian and Eritean - Saint Phillip (Phillip the Evangelist) is believed to have baptized an Ethiopian pilgrim.
4. Syriac - Antioch is mentioned in the Book of Acts as the place where Christians were first known as “Christians”.
5. Indian Orthodox - Saint Thomas was martyred in Southern India.
6. The British Orthodox Church - canonically part of the Coptic Orthodox Patriarchate of Alexandria.

The Oriental Orthodox Churches were one with the Roman and Byzantine churches until the 5th century when they separated based on a difference in belief. The Roman and Byzantine Church came to accept Chalcedon as the Fourth Ecumenical Council. The Oriental Orthodox Churches only acknowledge the first three. The Council of Chalcedon stated that Christ had two distinct natures, human and divine and He was united as one person. The Oriental Orthodox Churches believe to this day, that Christ only has one nature, at once human and divine. According to this difference in belief, the Oriental Orthodox Churches are commonly referred to as “non-Chalcedonian”.

The six churches which make up the Oriental Orthodox Churches are in full communion with one another even though they are completely independent in hierarchy. They are currently considered to be in partial communion with the Churches of Rome and Byzantine since the Chalcedonian schism is not seen with the same importance now. In the 20th century, after many meetings between the authorities of the different churches it came to their attention that the schism was based more on differences in terminology and culture and did not directly affect the substance of their faith. It is more accepted that the main reason for the schism between the Oriental Orthodox Churches and the Roman and Byzantine Churches occurred when the bishops of the Roman and Byzantine Churches excommunicated the non-Chalcedonian bishops therefore declaring them to be out of communion since they refused to accept the Fourth Ecumenical Council of Chalcedon. In 1964, the excommunications made by the Roman and Byzantine churches were lifted so it is regarded that the churches are in a state of partial communion with the other patriarchates even though full communion has not been restored.