The creators of Assyrian theology are Diodorus of Tarsus and Theodore of Mopsuestia. Both taught at Antioch. The normative Christology of the Assyrian church was written by Babai the Great (551–628) and is clearly different from the accusations of dualism directed toward Nestorius: his main christological work is called the 'Book of the Union', and in it Babai teaches that the two "qnome" (essences) are unmingled but everlastingly united in the one "parsopa" (personality) of Christ.