Virgin Birth

The Anglican Archbishop of Canterbury said that he didn't think that the Virgin Birth was necessary for one to believe in the Anglican Communion. He also made other comments about the number of the Magi, where they were from, and other matters. All of these comments were fine, but I am slightly confused as to how one can deny the Virgin Birth and remain an orthodox Christian. If Christ had an Earthly father, where did His divinity come from? It seems that to deny the Virgin Birth is to either deny logic or believe that Christ was adopted into the Godhead, instead of being God from the moment of His conception. This seems to downplay God's deep love for us, as the Incarnation, that God would be a zygote, shows His great humility.