The Mother of God--rightly called

I have been amazed that some are utterly in doubt as to whether or not the holy Virgin is able to be called the Mother of God.  For if our Lord Jesus Christ is God, how should the holy Virgin who bore him not be the Mother of God? Letter to the Monks of Egypt 1 (A.D. 427)  St. Cyril of Alexandria

You cannot then help admitting that the grace comes from God. It is God, then, who has given it. But it has been given by our Lord Jesus Christ. Therefore the Lord Jesus Christ is God. But if he is God, as he certainly is, then she who bore God is the Mother of God On the Incarnation of Christ: Against Nestorius 2:2 (A.D. 429)  St. John Cassian