7 The question which Faustus makes it appear that he is asked by a Catholic, If Jesus was not born, how could He die? Could be asked only by one who overlooked the fact that Adam died, though he was not born. Who will venture to say that the Son of God could not, if He had pleased, have made for Himself a true human body in the same way as He did for Adam; for all things were made by Him? or who will deny that He who is the Almighty Son of the Almighty could, if He had chosen, have taken a body from a heavenly substance, or from air or vapor, and have so changed it into the precise character of a human body, as that He might have lived as a man, and have died in it?
Or, once more, if He had chosen to take a body of none of the material substances which He had made, but to create for Himself from nothing real flesh, as all things were created by Him from nothing, none of us will oppose this by saying that He could not have done it. The reason of our believing Him to have been born of the Virgin Mary, is not that He could not otherwise have appeared among men in a true body, but because it is so written in the Scripture, which we must believe in order to be Christians, or to be saved.
We believe, then, that Christ was born of the Virgin Mary, because it is so written in the Gospel; we believe that He died on the cross, because it is so written in the Gospel; we believe that both His birth and death were real, because the Gospel is no fiction. Why He chose to suffer all these things in a body taken from a woman is a matter known only to Himself. Perhaps He took this way of giving importance and honor to both the sexes which He had created, taking the form of a man, and being born of a woman; or there may have been some other reason, we cannot tell.
But this may be confidently affirmed, that what took place was exactly as we are told in the Gospel narrative, and that what the wisdom of God determined upon was exactly what ought to have happened. We place the authority of the Gospel above all heretical discussions; and we admire the counsel of divine wisdom more than any counsel of any creature.
Source: Reply to Faustus the Manichaean (New Advent)