Like the Coptic and Ethiopian churches, the Armenian church did not accept the Council of Chalcedon's formula of 451 describing two natures, divine and human, united in Christ, holding instead to a miaphysite Christology of one united nature. Armenian bishops were not present at Chalcedon itself, occupied that year with a related but distinct struggle: the Battle of Avarayr, in which Armenian forces resisted Sassanid Persian pressure to abandon Christianity for Zoroastrianism. Vardan Mamikonian, the general who died leading that resistance, is venerated as a martyr saint, and the battle is remembered as a defense of Christian identity even though it was fought the same year theological Chalcedon was deciding the question that would separate Armenia from Byzantine orthodoxy.
The church is led today by two Catholicoi, at Etchmiadzin in Armenia and at Antelias in Lebanon, a division rooted in medieval and early modern political upheaval rather than doctrine, together with two additional Patriarchates, of Jerusalem and of Constantinople, that hold ceremonial primacy without full Catholicos authority.
The Armenian Genocide of 1915, in which Ottoman authorities killed and deported the empire's Armenian population including a large proportion of the church's clergy, scattered survivors across a global diaspora. The church today serves that diaspora as much as Armenia itself, and its cathedrals from Jerusalem to Los Angeles remain central to Armenian communal identity worldwide.