Catholicos of All Armenians

The Catholicos of All Armenians leads the Armenian Apostolic Church, the national church of the Armenian people and, by traditional reckoning, one of the oldest state churches in the world. Armenian tradition holds that the apostles Thaddeus and Bartholomew first brought Christianity to Armenia in the first century CE, and that Gregory the Illuminator converted King Tiridates III and the Armenian court around 301 CE, an event Armenian tradition dates earlier than the Roman Empire's own toleration of Christianity under Constantine. Gregory became the church's first Catholicos, and Armenian Christianity has remained closely bound to Armenian national identity through subsequent centuries of foreign rule by Persian, Byzantine, Arab, Mongol, Ottoman and Russian powers.

Like the Coptic Church, the Armenian Apostolic Church did not accept the christological formula of the Council of Chalcedon in 451 CE and is counted among the Oriental Orthodox churches, a family distinct from both Roman Catholicism and Eastern (Chalcedonian) Orthodoxy despite the similarity of names. The church's seat, Etchmiadzin, near Armenia's capital Yerevan, houses what is traditionally regarded as the oldest cathedral in the world, founded in the early fourth century.

The Catholicos of All Armenians is elected by a National Ecclesiastical Assembly, a body of clergy and lay delegates drawn not only from Armenia itself but from Armenian communities across the global diaspora, a structure reflecting the reality that the majority of Armenians have lived outside Armenia's borders for much of the modern era, particularly following the Armenian genocide of 1915 to 1917 under the Ottoman Empire, which killed an estimated one to one and a half million Armenians and scattered survivors across the Middle East, Europe and the Americas.

A second, jurisdictionally distinct Catholicosate exists at Cilicia, now seated at Antelias near Beirut, Lebanon, tracing its own continuous line to a medieval Armenian kingdom in Cilicia, in present-day southern Turkey; the split reflects historical political geography rather than a live succession dispute, and the two Catholicosates recognize each other and coordinate on matters of shared doctrine and liturgy while each governs its own jurisdiction, primarily Middle Eastern and diaspora communities for Cilicia and Armenia proper plus most of the wider diaspora for Etchmiadzin.

Two further sees carry the Catholicos title within Armenian Christianity without claiming the primacy of All Armenians: the Armenian Patriarchate of Jerusalem and the Armenian Patriarchate of Constantinople hold patriarchal rather than catholicosal rank and administer specific historic communities rather than the church as a whole. Both defer to Etchmiadzin on questions of doctrine, underscoring that the Armenian Apostolic Church's several senior sees form a single communion with distributed administrative seats rather than several competing claims to the same office.