to a virgin pledged to be married to a man whose name was Joseph, of the house of David. The virgin's name was Mary.
The Old Testament identified the coming redeemer as Immanuel (meaning "God with us"), Mighty God, Everlasting Father, etc.   (Isaiah 9:6; 1:14f); and this identification was continued in the New Testament where Jesus Christ is referred to no less than ten times as "God."  How could God have become a man if not by means of a virgin birth?  The pre-existence of Christ "before the world was" (John 17:5) made it an impossibility for him to have entered earth life as a result of the normal processes of procreation in which the union of two mortals, male and female, is utterly incapable of producing a life which had already existed.  A denial of the virgin birth is a denial of the deity of Jesus Christ.