"The virgin will be with child and will give birth to a son, and they will call him Immanuel"–which means, "God with us."
Rather than make Jesus look good and the rest of us bad, the Virgin Birth points up our inherent divinity—all of us, not just Jesus. We can no longer say that we are only human and use that as an excuse to ignore the higher part of our nature. By insisting that the Virgin Birth is strictly an external event, we hold the experience at arm’s length, and thereby avoid having to surrender to the Indwelling Spirit’s urge to open our eyes to the world of God.
Mary’s acquiescence to Gabriel’s proclamation is our own willingness to receive the Word—not the written word of the Bible (or any other sacred text) but the divine impulse, that which fuels our spiritual/physical evolution—”the force that through the green fuse drives the flower…” of Dylan Thomas. If we look at it in this way, the Virgin Birth story tells us emphatically that the Life Force is anything but blind, that life is imbued with intelligence and motivated by love.
Whether parthenogenesis (asexual reproduction) is possible in humans is a scientific question, even if we approach it spiritually. We can ask if one can cause pregnancy by speaking the Word, or if a female initiate of high degree, as Mary is reported to have been, can self-induce pregnancy. The theological assertion that God Himself through miraculous means fathered Jesus implies that the natural world is different and separate from the Causal Plane, which is scientifically implausible.
Philosophically, we could say that the story of Jesus’ birth reinforces the idea that our physical bodies are vehicles for our soul, that our origin is divine, and that who we are is not a mere product of biochemistry. But all of these notions are themselves meaningless, unless we can actually have the experience that they point to. They are all interpretations of an event that must take place in us, if we are to know God. Our physical body is the “world” into which the savior is born; the Cave of the Nativity is the center of our being.
The Mystical Christ 
Obviously, this story isn’t really about Jesus and/or Mary; it’s about us–our virgin birth. What we know about Mary is what we ourselves must become–“know(ing) no man”–before the Master can be born in us; which is to say, before we can become the master. The Christ Self cannot be born in our awareness until our minds have been purified; until we have surrendered the ego to God.
This is why we take the vows you have been discussing here: to become (like) Mary; pure, virginal, Self-contained. As this occurs, we discover the Star within and, like wise men (and women) we follow it, sensing it contains our Source, like the seed buried in the darkness of winter, awaiting the quickening of spring. The birth of Jesus, then, is the Illumination when the seed bursts forth, exploding like a thousand suns within us, filling our entire beings with the Light of Christ, the Son/Sun of God. (It is said by the mystics of old, by the way, that Jesus was actually born at the Spring Equinox, which is more in keeping with the symbology discussed here).
The story of virgin Mary and Jesus is real. But we must follow the spiritual side of the story. So accepting Jesus as a Saviour is a good start. As Apostle Paul did. And Christ in him was Born