The Council of Seleucia-Ctesiphon, also called the…

The Council of Seleucia-Ctesiphon, also called the Council of Mar Isaac, meets in 410 in Seleucia-Ctesiphon, the capital of the Sassanid Empire of Persia.

The council extends official recognition to the Empire's Christian community, later to be known as the Church of the East, and establishes the Bishop of Seleucia-Ctesiphon as its Catholicos, or leader.

It marks a major milestone in the history of the Church of the East and of Christianity in Asia in general.

The council is called by Mar Isaac, bishop of Seleucia-Ctesiphon, who is then declared as the primate of the Sassanid church, confirming him as Catholicos and Archbishop of all the Orient.

The decision is substantial, as Christians in the Sassanid Empire up to that point are fairly disorganized and persecuted, and Zoroastrianism is instead the primary religion of the Empire.

In 409, permission had been formally given by the Zoroastrian King Yezdegerd to the Christians to even exist: to worship openly, and to rebuild destroyed churches, though they are not allowed to proselytize.

The Synod also declares its adherence to the decisions of the Council of Nicea and subscribes to the Nicene Creed.