The Synod of Seleucia-Ctesiphon (also called the Synod of Mar Isaac) met in AD 410 under the presidency of Mar Isaac, the bishop of Seleucia-Ctesiphon. The most important decision of the Synod which had a very far reaching effect on the life of the church, was to declare the bishop of Seleucia-Ctesiphon as the primate of the Sassanid church; and in recognition of this he was given the title ‘Catholicos’. The Synod confirmed Mar Isaac as Catholicos and Archbishop of all the Orient. The Synod declared its adherence to the decisions of the Council of Nicea and subscribed to the Nicene Creed.