That anyone could doubt the right of the holy Virgin to be called the Mother of God fills me with astonishment. Surely she must be the Mother of God if our Lord Jesus Christ is God, and she gave birth to him! Our Lord's disciples may not have used those exact words, but they delivered to us the belief those words enshrine, and this has also been taught us by the holy fathers.
In the third book of his work on the holy and consubstantial Trinity, our father Athanasius, of glorious memory, several times refers to the holy Virgin as "Mother of God." I cannot resist quoting his own words: "As I have often told you, the distinctive mark of holy Scripture is that it was written to make a twofold declaration concerning our Savior; namely, that he is and has always been God, since he is the Word, Radiance and Wisdom of the Father; and that for our sake in these latter days he took flesh from the Virgin Mary, Mother of God, and became human." ...
The divinely inspired Scriptures affirm that the Word of God was made flesh, that is to say, was united to a human body endowed with a rational soul. He undertook to help the descendants of Abraham, fashioning a body for himself from a woman and sharing our flesh and blood, to enable us to see in him not only God, but also, by reason of this union, a human being like ourselves.
It is held, therefore, that there are in Emmanuel two entities, divinity and humanity. Yet our Lord Jesus Christ is nonetheless one, the one true Son, both God and human; not a deified human on the same footing as those who share the divine nature by grace, but true God who for our sake appeared in human form. We are assured of this by Saint Paul's declaration: "When the fullness of time came, God sent his Son, born of a woman, born under the law, to redeem those who were under the law and to enable us to be adopted as children."
edited by J. Robert Wright (Church Publishing, 1991), p. 486.
Many thanks to Catholicity and Covenant for noting how Richard Hooker affirms St. Cyril's words and the Christological teaching of the Third Ecumenical Council of Ephesus (431). He writes:
The faith of Cyril and Ephesus, affirmed by Hooker, does pose some questions for those Anglicans - liberal and evangelical - who flee from describing the Blessed Virgin as Theotokos/God bearer. Liberals, we can suppose, dislike the creedal Christology inherent in the title: that begs quite a few very significant questions indeed. For evangelical Anglicans, however, surely an orthodox affirmation of the Incarnation requires - as Cyril, Ephesus, and Hooker state - a recognition that the girl from Nazareth was indeed Theotokos? That the phrase is not used in Scripture is of little significance - nor is homousion. It is also difficult to avoid Hooker's conclusion that a rejection of Ephesus means "we are plainly and inevitably Nestorians".
And for catholic Anglicans ... well, we need to be challenged to re-engage with the Christological roots of Marian belief and devotion. It is not an ecclesiastical hobby nor a badge of ecclesial identity. We confess Mary as Theotokos not to be like Romans, not to declare that we are 'High', but because "for us and for our salvation" the Word became flesh. We confess Mary as Theotokos to remind the Church of her Christological centre.