14. It is well known what is meant by giving birth. Mary's experience was not different from that of other women, so that the birth of Christ was a real natural birth, Mary being his natural mother and he being her natural son. Therefore her body performed its functions of giving birth, which naturally belonged to it, except that she brought forth without sin, without shame, without pain and without injury, just as she had conceived without sin. The curse of Eve did not come on her, where God said: "In pain thou shalt bring forth children," Gen. 3: 16; otherwise it was with her in every particular as with every woman who gives birth to a child.15. Grace does not interfere with nature and her work, but rather improves and promotes it. Likewise Mary, without doubt, also nourished the child with milk from her breast and not with strange milk, or in a manner different from that which nature provided, as we sing: ubere de coelo pleno, from her breast being filled by heaven, without injury or impurity. I mention this that we may be grounded in the faith and know that Jesus was a natural man in every respect just as we, the only difference being in his relation to sin and grace, he being without a sinful nature. In him and in his mother nature was pure in all the members and in all the operations of those members. No body or member of woman ever performed its natural function without sin, except that of this virgin; here foronce God bestowed special honor upon nature and its operations. It is a great comfort to us that Jesus took upon himself our nature and flesh. Therefore we are not to take away from him or his mother any thing that is not in conflict with grace, for the text clearly says that she brought him forth, and the angels said, unto you he is born.16. How could God have shown his goodness in a more sublime manner than by humbling himself to partake of flesh and blood, that he did not even disdain the natural privacy but honors nature most highly in that part where in Adam and Eve it was most miserably brought to shame? so that henceforth even that can be regarded godly, honest and pure, which in all men is the most ungodly, shameful and impure. These are real miracles of God, for in no way could he have given us stronger, more forcible and purer pictures of chastity than in this birth. When we look at this birth, and reflect upon how the sublime Majesty moves with great earnestness and inexpressible love and goodness upon the flesh and blood of this virgin, we see how here all evil lust and every evil thought is banished.17. No woman can inspire such pure thoughts in a man as this virgin; nor can any man inspire such pure thought in a woman as this child. If in reflecting on this birth we recognize the work of God that is embodied in it, only chastity and purity spring from it.18. But what happens in heaven concerning this birth? As much as it is despised on earth, so much and a thousand times more is it honored in heaven. If an angel from heaven came and praised you and your work, would you not regard it of greater value than all the praise and honor the world could give you, and for which you would be willing to bear the greatest humility and reproach? What exalted honor is that when all the angels in heaven can not restrain themselves from breaking out in rejoicing, so that even poor shepherds in the fields hear them preach, praise God, sing and pour out their joy without measure? Were not all joy and honor realized at Bethlehem, yes, all joy and honor experienced by all the kings and nobles on earth, to be regarded as only dross and abomination, ofwhich no one likes to think, when compared with the joy and glory here displayed?19. Behold how very richly God honors those who are despised of men, and that very gladly. Here you see that his eyes look into the depths of humility, as is written, "He sitteth above the cherubim" and looketh into the depths. Nor could the angels find princes or valiant men to whom to communicate the good news; but only unlearned laymen, the most humble people upon earth. Could they not have addressed the high priests, who it was supposed knew so much concerning God and the angels? No, God chose poor shepherds, who, though they were of low esteem in the sight of men, were in heaven regarded as worthy of such great grace and honor.
Read the rest of Martin Luther's Christmas sermon