Most Armenians are Christians, primarily of Oriental Orthodox rite. Christianity was first introduced by the apostles Bartholomew and Thaddeus in the 1st century AD. Armenia became the first country to establish Christianity as its state religion  when, in an event traditionally dated to 301 AD, St. Gregory the Illuminator convinced  Tiridates III, the king of Armenia, to convert to Christianity. Before this the dominant  religion was Zoroastrianism and to a smaller degree Paganism.  Thanks to the sermons of Gregory the Illuminator, Armenian king Tiridates (287-330 A.D.) and his family were the first to be baptized, after which Christianity was announced as the state religion of the country.

Christianity has a strong influence in the country, but there is a small presence of other religions, too. Thus, over 90% of Armenians belong to the Armenian Apostolic Church, a form of Oriental (Non-Chalcedonianism) Orthodoxy, other Christian 4% (mostly Armenian Catholic and Russian Orthodox), Yazidi (monotheist with elements of nature worship) 1.3%, and small Muslim and Jewish populations. Armenia also has a population of Catholics and evangelical Protestants.

The Mother See of Holy Echmiadzin is the pre-eminent center of authority in the worldwide Armenian Apostolic Church. It is composed of (a) the Mother Cathedral of the entire Armenian Church; (b) a monastery and monastic brotherhood; (c) the residence of the Catholicos of All Armenians; and (d) various religious and cultural institutions, such as the Kevorkian Theological Seminary and a museum.