Separation, Persian Rule and a Church's Own Councils

The Church of the East's rejection of Ephesus in 431 did not leave it without any conciliar life of its own, only without any further councils it recognised as binding on the wider Christian world's faith. The Church of the East: An Illustrated History of Assyrian Christianity records that the church went on holding its own synods, most notably at Seleucia-Ctesiphon in Persian territory, gatherings that settled matters of canon law, clerical discipline and church administration for a community that found itself, after the separation, outside the Roman Empire's borders entirely and under first Persian Sasanian and later Islamic rule. That political location shaped the separation as much as theology did: a church whose faithful lived under a rival empire to Rome had practical reasons, well documented by historians of the period, to distance itself from a christological formula tied to the emperor's own church, whatever the formula's theological merits. The Oxford Dictionary of the Christian Church notes that this history left the Church of the East doctrinally settled at 381 in a technical sense while remaining administratively and liturgically alive across Persia, Central Asia and eventually as far as China through missionary expansion, a church whose creed stopped growing centuries before its geography did.