The precise Christological teachings of Nestorius are shrouded in obscurity. Wary of monophysitism, Nestorius rejected Cyril's theory of a hypostatic union, proposing instead a much looser concept of prosopic union. Nestorianism has come to mean radical dyophysitism, in which Christ's two natures are eternally separate, though it is doubtful whether Nestorius ever taught such a doctrine. Nestorius' rejection of the term Theotokos ('God-bearer', or 'Mother of God') has traditionally been held as evidence that he asserted the existence of two persons (dyoprosopism) — not merely two natures — in Jesus Christ, but there exists no evidence that Nestorius denied Christ's oneness. In the controversy that followed the Council of Ephesus, the term "Nestorian" was applied to all doctrine upholding a strictly Antiochene Christology. In consequence, the Church of the East was labelled Nestorian, though its official Christology was in fact defined by Babai the Great, at the council that was held in 612.