Council of Seleucia-Ctesiphon

The Council of Seleucia-Ctesiphon, also called the Council of Mar Isaac, met in AD 410 in Seleucia-Ctesiphon, the capital of the Sassanid Empire of Persia. The council extended official recognition to the Empire's Christian community, known as the Church of the East, and established the Bishop of Seleucia-Ctesiphon as its Catholicos, or leader. It marked a major milestone in the history of the Church of the East and of Christianity in Asia in general.

The council was called by Mar Isaac, bishop of Seleucia-Ctesiphon, and who was then declared as the primate of the Sassanid church, confirming him as Catholicos and Archbishop of all the Orient. The decision was substantial, as Christians in the Sassanid Empire up to that point were fairly disorganized and persecuted, and Zoroastrianism was instead the primary religion of the Empire. In 409, permission was formally given by the Zoroastrian King Yazdegerd I to the Christians to even exist; to worship openly, and to rebuild destroyed churches, though they were not allowed to proselytize.

The synod also declared its adherence to the decisions of the First Council of Nicaea and adopted a form of the Nicene Creed. The creed is found in two different recensions, both of them recorded in much later manuscripts. First recension is East Syriac and comes from the Church of the East sources. Second is West Syriac and comes from Syrian Orthodox sources. The East Syriac recension contains: "And in the Holy Spirit" while the West Syriac recension contains: "And we confess the living and Holy Spirit, the living Paraclete, who is from the Father and the Son". There has been a long controversy among scholars over the relationship between these two texts. The development of a Persian creed is difficult to track since there were several recensions prior to 410. First recension is textually closer to original Nicene Creed. On the other hand, some scholars are claiming that second recension represents the original. Further more, they claim that words "who is from the Father and the Son" in the second recension represent the earliest example of the Filioque clause. Since wording "who is from the Father and the Son" does not contain any mention of the term "procession" or any of the other particular terms that would describe relations between Father, Son and the Holy Spirit, the previously mentioned claim for the "earliest example" of Filioque clause is not universally accepted by the scholars.

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