10 Faustus cannot pretend then I am unable to prove that Mary was of the family of David, as I have shown him unable to prove that she was not. I produce the strongest evidence from Scriptures of established authority, which declare that Christ was of the seed of David, and that He was born without a father of the Virgin Mary. Faustus expresses what he considers a most becoming indignation against impropriety when he says, It is an injurious misrepresentation of the writer to make him speak of the Son of God as the inmate of a womb.
Of course, the Catholic doctrine which teaches that Christ the Son of God was born in the flesh of a virgin, does not make the Son of God the inmate of her womb in the sense of having no existence beyond it, as if He had abandoned the government of heaven and earth, or as if He had left the presence of the Father. The mistake is with the Manichæans, whose understanding is so incapable of forming a conception of anything except what is material, that they cannot comprehend how the Word of God, who is the virtue and wisdom of God, while remaining in Himself and with the Father, and while governing the universe, reaches from end to end in strength, and sweetly orders all things. In the faultless procedure of this adorable providence, He appointed for Himself an earthly mother; and to free His servants from the bondage of corruption He took in this mother the form of a servant, that is, a mortal body; and this body which He took He showed openly, and when it had been exposed, even to suffering and death, He raised it again from the dead, and built again the temple which had been destroyed.
You who shrink from this doctrine as blasphemous, make the members of your god to be confined not in a virgin's womb, but in the wombs of all female animals, from elephants down to flies. Perhaps you think the less of the true Christ, because the Word is said so to have become incarnate in the Virgin's womb as to provide a temple for Himself in human nature, while His own nature continued unaltered in its integrity; and, on the other hand, you think the more of your god, because in the bonds and pollution of his confinement in flesh, in the part which is to be made fast to the mass of darkness, he seeks for help to no purpose, or is even rendered powerless to ask for help.
Source: Reply to Faustus the Manichaean (New Advent)