‘Moreover we confess that the Son of God was born of the blessed Virgin and we do not hesitate to call Mary the Mother of God.’ So says Peter Martyr Vermigli in his Dialogue on the Two Natures in Christ (Thomas Jefferson University Press, 1995; reprinted by the Davenant Institute), Topic II: On the Property of the Natures in Christ, 2:59.
This is Reformed. Both the theology and the practice are 100% Protestant.
Some Protestants may object that the point is fruitless and unnecessary to make, and that the title Mother of God is both needless and confusing. When would it be relevant and ædifying?
Suppose that we reflect on the Incarnation over several weeks. Suppose that we come to the thought that God the Son deigned to be born of a woman: as the hymn Te Deum says, ‘When thou tookest upon thee to deliver man, thou didst not abhor the Virgin’s womb.’ Then suppose that we look at the same event from the other end: God gave a woman, living under the curse placed upon Eve, the privilege of becoming the Mother of her own Creator. Viewed this way, Mary’s becoming the Mother of God is one part of Christ’s fulfilment of Psalm 8, where the Psalmist says,
What is man, that thou art mindful of him?
and the son of man, that thou visitest him?
For thou hast made him a little lower than the angels,
and hast crowned him with glory and honour.
Is this not what God the Son began to do in becoming the son of a woman, and what he completed in ascending to the right hand of God the Father to reign over heaven and earth as a man? Already in Mary’s becoming the Mother of He-Who-Is-God, Christ was beginning to crown mankind with a glory and honour that was until then unimaginable.
Perhaps that doesn’t do much for you, and you may feel unsure why it should.
But Luke 1.42–43, I think, encourages us to have the same response of the heart as Elizabeth had, mutatis mutandis. Jesus is so holy, and he has both received and conferred such privilege for believing mankind, that even the arrival of his holy vessel elicits from Elizabeth the exclamation, ‘Blessed art thou among women, and blessed is the fruit of thy womb. And whence is this to me, that the mother of my Lord should come to me?’ It is a godly and indeed prophetic response to the dignity with which Christ, by his incarnation in the womb of a woman, has crowned Mary and all mankind. May these contemplations, called to memory by Mary’s title ‘Mother of God’, magnify God’s holy Name and cause our spirits to rejoice in God our Saviour, through Jesus Christ our Lord.