We’re just now beginning to anticipate the birth of Christ, and Barth concludes part 2 of the Church Dogmatics with an unpacking of the incarnational mystery: Jesus Christ, the eternal Son, was conceived by the Holy Spirit and born of the virgin Mary.
Karl Barth’s high Christology, his primary way of identifying Jesus Christ as the ‘God-Man’ according to the Chalcedon definition, leads Barth to put more emphasis on the virgin birth than you might expect from a Protestant.
Whereas most Protestants reduce the incarnation to its utility- Jesus is born to die, for us- Barth sees the very becoming human of the eternal, preexistent Word is itself God’s revelation.
Therefore, says Barth, the incarnation is “the prime mystery” and “our reconciliation” (§15.3).
Indeed Barth’s marveling over the incarnation leads him in a direction that seems more Patristic than Protestant, nearly implying that the incarnation itself is salvific.
Throughout §15 Barth argues that the virgin birth is the bible’s way of pointing to the mystery and revelation that Jesus is the incarnate God-Man.
In other words, the virgin birth is so important to Barth because if the Son (as in, not Mary’s son but the 2nd Person of the Trinity) is the Father’s preexistent, eternal decision to be ‘God-for-us’ in which heaven and earth, finite and infinite, are united then the incarnation is more than just the curtain rising on a drama where all the importance stuff happens in Act 3 or 4.
The incarnation is itself revelatory.
And maybe even salvific.