One of the more peculiar teachings of the Christian faith, affirmed throughout all of the creeds, is the fact that Christ was born of the virgin Mary. Meaning, Mary had not had any relations before she gave birth to Christ.
Both Matthew and Luke agree on this fact. In Luke’s account, the angel Gabriel announces that Mary will birth a child. Mary, not being married, rightly asks: “How can this be, since I am still a virgin?” (Lk 1:34). Gabriel answers: “The Holy Spirit will come upon you, and the power of the Most High will overshadow you; therefore the child to be born will be called holy — the Son of God” (v. 35).
Matthew’s account is similar. He adds the detail the her virginal birth is in fulfillment of prophecy: “Behold, the virgin shall conceive and bear a son, and they shall call his name Immanuel” (Mt 1:23).
There is not much more information about the virgin birth in the epistles. Some say that Paul alludes to it in Galatians 4:4, or that John references Mary in Revelation 13. But there are not really any more details about this. It is simply stated in the gospel accounts.
Many have speculated, with such scarce reference in the New Testament, what is the purpose of the virgin birth? Or, to say it another way: did Mary have to be a virgin to give birth to Christ? Was there some necessity to it? Did the virginal birth, as some presume, in some way preserve the divinity of Christ? Or preserve the sinlessness of Christ?
Frederick Bruner has an interesting examination of the doctrine in his commentary on Matthew, Christbook. His estimation is that the reason for the virgin cannot be found in preserving Christ’s divinity or sinlessness. He aptly points out:
If the first Adam — whoever he was — came into being without two human parents and yet was truly human, why could not Jesus the last Adam be without a single human parent and still be truly human? “Is anything too hard for the Lord?” (Gen 18:14) (pp 39)
In other words, Jesus could come into the world in really any way he wanted, and be fully God and fully man, sinless. God, after all, is omnipotent!
So then, why the virginal birth? Bruner cites Karl Barth, saying:
The virgin birth teaches an immensely important doctrinal truth: that in human salvation “the initiative is wholly with God”. The doctrine of the virgin birth, in a striking metaphor, stands “on guard” before the door of the mystery of Jesus’ divinely wrought salvation — only God can work salvation, and this is exactly what the Christmas stories’ virgin birth teaches with a dramatic eloquence. (pp 40)
In other words, the incarnation of Christ is a complete work of God. Because she was a virgin, Mary was merely a recipient of God’s grace. Man had nothing to do with it.
Joseph Ratzinger, in his Introduction to Christianity, agrees with this. He says:
The Virgin Birth is not a lesson in asceticism, nor does it belong directly to the doctrine of Jesus’ divine Sonship; it is first to last a theology of grace, a proclamation of how salvation comes to us: in the simplicity of acceptance,as the voluntary gift of the love that redeems the world… In Jesus, God has placed, in the midst of barren, hopeless mankind, a new beginning that is not a product of human history but a gift from above. (pp 278)
Because of this, Ratzinger concludes that Mary herself is an image of the church. He says:
As the true “daughter of Zion”, Mary is the image of the Church, the image of believing man, who can come to salvation and to himself only through the gift of love — through grace.
I think that Bruner and Ratzinger both get to the bottom of the doctrine of the virginal birth: it is an action of grace. A unilateral action of God in which man is passive, having nothing to contribute. All is grace!