This is the word of the prophet: “Unto to us a child is born, unto to us a son is given” (Isa. 9:6). This is for us the hardest point, not so much to believe that he is the son of the virgin and God himself, as to believe that this Son of God is ours. That is where we wilt, but he who feels it has become another man. Truly it is marvelous in our eyes that God should place a little child in the lap of a virgin and that all our blessedness should lie in him. And this Child belongs to all mankind. God feeds the whole world through a Babe nursing at Mary’s breast. This must be our daily exercise: to be transformed into Christ, being nourished by this food. The will the heart be suffused with all joy and will be strong and confident against every assault.

Martin Luther in his Christmas Book

in Come, Thou Long-Expected Jesus, ed. Nancy Guthrie, (Wheaton: Crossway, 2008), 26-27.