The Armenian Apostolic Church (Armenian: Հայ Առաքելական Եկեղեցի, romanized: Hay Aṙak’elakan Yekeghetsi) is the national church of the Armenian people. Part of Oriental Orthodoxy, it is one of the most ancient Christian institutions.
The Kingdom of Armenia was the first state to adopt Christianity as its official religion under the rule of King Tiridates III of the Arsacid dynasty in the early 4th century. According to tradition, the church originated in the missions of Apostles Bartholomew and Thaddeus of Edessa in the 1st century.
It is sometimes referred to as the Armenian Orthodox Church or the Armenian Gregorian Church. The term Gregorian Church is not preferred by the church itself, as it views the Apostles Bartholomew and Thaddeus as its founders, and St. Gregory the Illuminator as merely the first official governor of the church. It is also known simply as the Armenian Church.