Recommended Book: First Epistle of Clement to the Corinthians - Kindle Edition (get Kindle app for phone) (paid link)

If anyone disbelieves that Holy Mary is the Mother of God, such a one is estranged from the Godhead. Were anyone to say that [Christ] passed through the Virgin as through a channel and was not formed in her both in divine and human fashion--'divine' because without a husband's cooperation--'human' because conceived in accordance with human law-- such a one too is an atheist. Should anyone say that a man was made, and that God afterwards entered into him-- he is risking damnation.

Saint Gregory Nazianzen (325-389)