The Apostolic Church was organized in the third century and became autocephalous as a national church in the fourth century. In the sixth century it modified the formulations of the Council of Chalcedon of 451 that confirmed the dual nature of Christ in one person. Instead the Apostolic Church adopted a form of Miaphysitism that believes in the united nature of divine and human in Christ, a belief shared by the Copts and the Syrian Orthodox Church (Oriental Orthodox Church). The Armenian Orthodox Church has two catholicoi (Sis and Etchmiadzin Cathedral) and two patriarchs (Constantinople and Jerusalem).