When the Christian religion lurks the mystery of the birth of its god to our limits of knowledge, we should remind ourselves that more mysterious than a god is the birth itself.
A true mystery is an unsolvable contradiction.
To give birth to another man is a mystery in the most concrete way. While the new born is expected to live longer than its parents, we put our lives together with someone’s life as closest as possible in human relations, even if we never can know the entire life of our child. And even if we survive to the death of our children, the mystery remains or becomes greater, since we are dragged into the unbreakable state of misunderstanding how a life which seemed to be our own is took away from us and we are still alive and almost forget it.
Moreover, ignoring the fate of the child, its birth is a mystery at least for the reason that we rarely have the experience of accepting a different life than ours as if it would be our own.
To the last mystery, different cultures offers many solutions of taming the bewilderment it generates. However, the habits of educating and growing our children and the norms which regularize our behavior as parents are still insufficient for untying the mystery. As a proof, we always know that our life which is more precious to us than anything else becomes meaningless when the life of our children is in danger. Or, if we care for our lives more than for the life of our children, though we act in the name of the natural individualism, we normally have to face the most dreadful feeling of guilty (the social blame often replaces the lack of that feeling).
If we compare the mystery of human birth with that of the birth of a god, the second does not add more mysteriousness to the first. It just makes humans to change their habit of ignoring the unknown things as it is the birth itself. Thus, the human birth is finally praised and celebrated. If the forms of celebration are samples of irrationality or inferior spirituality, it does not matter so much, because who can rightly celebrate an unknown reality?