He then said:

They are further bound to maintain that the divine nature dwelt together with the human nature for nine months or so from the very start of the pregnancy, remaining with it in the place where the fetus is carried in the womb, and that the two were born side by side. Yet this runs contrary to their own claim that Mary gave birth to the Messiah only in respect of His humanity, not His divinity.

It may be objected that they could answer, “Only the humanity was born,” just as the Melkites say, “Only the humanity was crucified.” Even so, if contradiction cannot be avoided, the Nestorians are the less inconsistent; for the Melkites declare that the two natures are a single person, a single hypostasis, each united to the other. If, despite that, one nature can still be separated from the other in eating, drinking, crucifixion, and death, then one who says that they are two essences and two hypostases is even more justified in saying that one of them was born without the other.

He went on to say:

And if they should assert, “The union occurred when He was a fully formed fetus,” we reply: “Then God was a fetus before His birth; and if it is possible for Him to be carried in the womb, it is equally possible for Him to be born.”

One may therefore conclude: They do not contend that the two became one person, a single hypostasis; rather, they hold that there are two essences and two hypostases—hence they would never say that Mary carried a god in her womb,