"But Christ did not receive this majesty, to which he was exalted according to his humanity, only after his resurrection from the dead and his ascension, but when he was conceived in his mother's womb and became man and when the divine and human nature were personally united . . . the ancient teachers of the church have combined both words, 'communion' and 'union,' in expounding this mystery and have explained the one through the other (Irenaeus, Book IV, chap. 3; Anthanasius [sic] in his Letter to Epictetus; Hilary, On the Trinity, Book IX; Basil and Gregory of Nyssa, in Theodoret; John Damascene, Book III, chap. 19) . . .
"On account of this personal union and communion of the natures, Mary, the most blessed virgin, did not conceive a mere, ordinary human being, but a human being who is truly the Son of the most high God, as the angel testifies. He demonstrated his divine majesty even in his mother's womb in that he was born of a virgin without violating her virginity. Therefore she is truly the mother of God and yet remained a virgin."
- Person of Christ (Formula of Concord: SD, Art. VIII par. 8ff, Tappert, 593-5)