Why a virgin birth?

The top three answers are on the board, Evangel family. Why was the Messiah born of a virgin?

Christian: to fulfill the prophecy from Isa 7:14. {ding!}
Christiana: Uhhhhhh… {buzz! X}
Junior: Hmmm… {buzz! XX}
Jonny: Because . . . Mary was a virgin. {buzz! XXX}

Kitson family, you have a chance to steal. Why was the Messiah born of a virgin?

Jake: Jesus? {buzz! X}

I suspect many of us could offer several reasons why the incarnation was necessary (Gal 4:4-5 & Heb 2:14-18), but most of us would begin to sweat profusely if we had to explain the point of the virgin birth. The difficulty, of course, lies in the fact that both Matthew and Luke assert Christ’s supernatural birth but neither of them explains the significance of the miracle. Some might infer that a virgin birth was required for the Son’s incarnation and/or for his sinless incarnation, but those explanations are far from certain.

So why the virgin birth? In The Person of Christ, Donald Macleod acknowledges that like all the miracles in Jesus’ life, the virgin birth functions as a sign and draws from Karl Barth to offer three theological reflections on the virgin birth:

First, it is highlighting the essentially supernatural character of Jesus and the gospel. Alluding to Barth again, the virgin birth is posted on guard at the door of the mystery of Christmas; and none of us must think of hurrying past it. It stands on the threshold of the New Testament, blatantly supernatural, defying our rationalism, informing us that all that follows belongs to the same order as itself and that if we find it offensive there is no point in proceeding further. If our faith staggers at the virgin birth what is it going to make of the feeding of the five thousand, the stilling of the tempest, the raising of Lazarus, the transfiguration, the resurrection and, above all, the astonishing self-consciousness of Jesus? . . .

Secondly, the virgin birth is a sign of God’s judgment on human nature. The race needs a redeemer, but cannot itself produce one: not by its own decision or desire, not by the processes of education and civilization, not as a precipitate of its own evolution. The redeemer must come from the outside. Here, as elsewhere, ‘all things are of God.’ He provides the lamb (Gn 22:8). Barth is exactly right: ‘Human nature possesses no capacity for becoming the human nature of Jesus Christ.

Thirdly, the virgin birth is a sign that Jesus Christ is a new beginning. He is not a development of anything that has gone before. He is a divine intrusion: the last, great, culminating eruption of the power of God into the plight of man: ‘Man is involved only in the form of non-willing, non-achieving, non-creative, non-sovereign man, only in the form of man who can merely receive, merely be ready, merely let something be done to and with himself.’

Come and worship.