The Council of Ephesus (431)
The Fifth Anathema: Not a God-Bearing Man
If anyone dares to say that Christ is a God-bearing man, and not rather that he is true God, as the only Son by nature, because “the Word was made flesh” and “shares in flesh and blood just as we do”: let him be anathema.
Nestorius’s fifth counter-anathema: If anyone ventures to say that, even after the taking on of human nature, there is only one Son of God, namely the one who is Son by nature, that is, the Word, while he, since taking on the flesh, is certainly Emmanuel: let him be anathema.
Petavius: It is plain that this anathema is aimed at the blasphemy of Nestorius in which he said that Christ was Emmanuel in this sense: that a man was united and joined with God, just as God had been said to be with the prophets and other holy men and to have made his dwelling in them. So they were properly called Theophoroi, “God-bearers,” because, as it were, they carried God about with them; but no one single being was made out of the two. Instead, he held that our Lord, as man, was bound and united with God only by a sharing of dignity. Nestorius, in his counter-anathema, lays bare the hidden meaning of his heresy when he says that the Son of God is not one after the taking on of the humanity. For whoever denied that he was one no doubt thought that he was two.
Theodoret, in his criticism of this anathema, remarks that many of the ancient writers, Saint Basil among them, had used this very word, Theophoros, of the Lord. But the objection has no real foundation. Whether such a word is orthodox or not must be decided by the setting in which it is used, and also by the known opinions of the one who uses it. Expressions that are orthodox in a loose sense, and quite excusable before a heresy arises, may afterward become the very marks and watchwords of error. Petavius has pointed out how far from orthodox many of the earliest Christian writers were, at least in their words; and Bishop Bull defended them by the same line of argument I have just used, which Petavius himself uses in this very connection.