Christmas, by definition, is the celebration of a birth. We celebrate the birth of Jesus. But Jesus already had an existence, before He was born. He was with the Father in the beginning at Creation. He showed up on Earth in spiritual form before He was born as a baby. But Jesus needed a human birth to become a man so that He could demonstrate the greater power of God and the greater plan of God to deliver men from the grip of self and sin. You might say that Jesus was "born again".
First of spirit and then of flesh, His two births exactly mirror the two births we need.....first of flesh and then of spirit! He came from Heaven to earth that we, who start on earth might enter Heaven. It is our choice whether or not to accept the gift of His life and love....He didn't have to come to earth as a baby. That was a choice... and it is your choice as well, whether to respond to His great gift to you.
Micah 5:2b-4 ...Yet a ruler of Israel, whose origins are in the distant past, will come from you on my behalf...And he will stand to lead his flock with the Lord's strength, in the majesty of the name of the Lord his God.
He was twice born that you might also be!