05. Luke 1: Some Comments on the “Virginal Conception” of Jesus
“Virginal Conception” not “Virgin Birth” is the proper term. Jesus’ birth was a normal human birth. It was his conception by the Spirit that is unique.
“We affirm that Jesus was born of woman
as is every child,
yet born of God's power
as was no other child.” (A Declaration of Faith, ch,4, par.1)
“Luke does not stress Mary’s virginity to exalt her as one who is a pure and holy vessel and worthy to give birth to such a child. Her virginity is presented as an obstacle to conception that can only be overcome by the miraculous, creative power of God” (Garland, Luke: 2112-2114).
Karl Barth on the “Virgin Birth”
In the creeds the assertion of the Virgin Birth is plainly enough characterized as a first statement about the One who was and is and will be the Son of God. It is not a statement about how He became this, a statement concerning the basis and condition of His Sonship. It is a description of the way in which the Son of God became man.
The Holy Spirit has never been regarded or described by any serious Christian theologian as the divine Father even of the man Jesus. In the exposition of this dogma—and thoroughly in the sense of its New Testament presuppositions—it has been frequently and energetically explained that it might have pleased God to let His Son become man in some quite different way than in the event of the miracle attested as the Virgin Birth. It did in fact please Him to let Him become man in this way, but this event is not the basis of the fact that the One who there became man was the Son of God. It is the sign which accompanies and indicates the mystery of the incarnation of the Son, marking it off as a mystery from all the beginnings of other human existences. It consists in a creative act of divine omnipotence, in which the will and work of man in the form of a human father is completely excluded from the basis and beginning of the human existence of the Son of God, being replaced by a divine act which is supremely unlike a human action which might arise in that connexion, and in that way characterized as an inconceivable act of grace.
"Conceived by the Holy Ghost" does not, therefore, mean "begotten by the Holy Ghost." It means that God Himself—acting directly in His own and not in human fashion—stands at the beginning of this human existence and is its direct author. It is He who gives to man in the person of Mary the capacity which man does not have of himself, which she does not have and which no man could give her. It is He who sanctifies and ordains her the human mother of His Son. It is He who makes His Son hers, and in that way shares with humanity in her person nothing less than His own existence. he gives to her what she could not procure for herself and no other creature could procure for her. This is the miracle of the Virgin Birth as it indicates the mystery of the incarnation, the first attestation of the divine Sonship of the man Jesus of Nazareth, comparable with the miracle of the empty tomb at His exodus from temporal existence. The question is pertinent whether His divine Sonship and the mystery of His incarnation are known in any real seriousness and depth when these attestations of it are unrecognized or overlooked or denied or explained away. But in any case these attestations are based on His divine Sonship, not His divine Sonship on these attestations.
Karl Barth " Study Edition 21" Ed. T. F. Torrance and G.W. Bromiley. Trans. G. W. Bromiley. London: T & T Clark, 2010. 200-01. Print. 
Only Matthew and Luke have birth stories about Jesus. Neither Paul nor any other New Testament writer refers or alludes to Jesus’ virginal conception. What does this mean?
First, the gospel story can be told without it. Mark and John do it. So to, the gospel can be faithfully interpreted and applied without it (e.g. Paul).
Second, two gospels do have this story (in different forms). It is important to their telling of the Jesus-story. Indeed, their stories don’t quite make sense without it.
Third, as Barth remarks, “This is the miracle of the Virgin Birth as it indicates the mystery of the incarnation, the first attestation of the divine Sonship of the man Jesus of Nazareth, comparable with the miracle of the empty tomb at His exodus from temporal existence. The question is pertinent whether His divine Sonship and the mystery of His incarnation are known in any real seriousness and depth when these attestations are of it are unrecognized or overlooked or denied or explained away.” The mystery of the incarnation is the witness of this story. John, Mark, and Paul can affirm this mystery in other ways in their theologies. The statement above from A Declaration of Faith puts well the point of the virginal conception stories.
Fourth, it seems, then, that if the canon of scripture has two gospels that use virginal conception stories and two that do not, it would be a mistake to require adherence to it to be faithful to the gospel. Apparently, the gospel can be proclaimed and taught without it, as long as the reality which it expresses is present in it.
Fifth, that two gospels have this story mean it is not dispensable. It is a part of the apostolic testimony. Barth’s point that it bookends Jesus’ story at the front end with the resurrection at the back end counts in favor of taking it as realistically as we do the resurrection, in my judgment. As someone once put it: “If you can swallow the camel of the resurrection why strain at the gnat of the virginal conception?”
So . . . telling the story of Jesus may be told both in terms of his virginal conception and in other ways of expressing the same truth. And perhaps it should be told both ways. But we may justly allow each other some latitude here as to how realistically we take the birth stories as long as we all affirm their truth about Jesus as noted above.