Armenian Orthodox Church

The Armenian Orthodox Church, also called the Armenian Apostolic Church, is one of the original Oriental Orthodox churches, having separated from the then-still-united Catholic/Orthodox church in AD 451 by being excommunicated by the Council of Chalcedon, which accused the Armenian church of monophysitism. The head of the Armenian Orthodox Church is the Catholicos of Armenia (the plural is Catholicoi). The Coptic Orthodox Church was also excommunicated at the same time.

Armenia was the first country to adopt Christianity as its official religion, in AD 301, when Saint Gregory the Illuminator converted the king of Armenia to Christianity.