“The second promise of Christ was to Abraham, Genesis 22[:18], where God said, “In your seed shall all the Gentiles be blessed.” If all the Gentiles are to be blessed, then it is certain that otherwise, apart from this seed of Abraham, they were all unblessed and under a curse. From this it follows that human nature has nothing but cursed seed and bears nothing but unblessed fruit; otherwise, there would be no need for all of them to be blessed through this seed of Abraham. Whoever says “all” excludes no one; therefore, apart from Christ, all who are born of man must be under the devil, cursed in sin and death.

Here again the mother of God is proven to be a pure virgin. For since God cannot lie, it was inevitable that Christ should be the seed of Abraham, that is, his natural flesh and blood, like all of Abraham’s descendants. On the other hand, because he was to be the blessed seed which should bless all others, he could not be begotten by man, since such children, as has been said, cannot not be conceived without sin because of the corrupt and tainted flesh, which cannot perform its function without taint and sin.

Thus the word, by which God promises that Christ will be the seed of Abraham, requires that Christ be born of a woman and be her natural child. He does not come from the earth like Adam [Gen. 2:7]; neither is he from Adam’s rib like Eve [Gen. 2:21–22]. He comes rather like any woman’s child, from her seed. The earth was not the natural seed for Adam’s body; neither was Adam’s rib the natural seed for Eve’s body. But the virgin’s flesh and blood, from which children come in the case of all other women, was the natural seed of Christ’s body. And she too was of the seed of Abraham” (Luther’s Works, v.45 p.203-204).

“Now this passage [Gen. 3:15] was the very first gospel message on earth. For when Adam and Eve, seduced by the devil, had fallen and were summoned for judgment before God, Genesis 3[:9], they were in peril of death and the anguish of hell, for they saw that God was against them and condemned them; they would gladly have fled from him, but could not. Had God let them remain in their anguish, they would soon have despaired and perished. But when, after their terrible punishment, he let them hear his comforting promise to raise up from the woman’s seed one who would tread upon the serpent’s head, their spirits were quickened again. From that promise they drew comfort, believing firmly in that blessed seed of the woman which would come and crush the serpent’s head, that is, sin and death, by which they had been crushed and corrupted.

The fathers, from Adam on, preached and inculcated this gospel, through which they acknowledged the promised seed of this woman and believed in him. And so they were sustained through faith in Christ just as we are; they were true Christians like ourselves. Only, in their day this gospel was not proclaimed publicly throughout the world, as it would be after the coming of Christ, but remained solely in the possession of the holy fathers and their descendants down to the time of Abraham” (Luther’s Works, v.45 p.203).

“This seed of the woman therefore, because he is to crush the devil’s power, that is, sin and death, must not be an ordinary man, since all men have been brought under the devil through sin and death. So he must certainly be without sin. Now human nature does not produce such seed or fruit, as has been said, for with their sin they are all under the devil. How, then, can this be? The seed must be the natural child of a woman; otherwise, it could not be or be called the seed of the woman. On the other hand, as has been pointed out, human nature and birth does not produce such seed. Therefore, the solution must ultimately be that this seed is a true natural son of the woman; derived from the woman, however, not in the normal way but through a special act of God, in order that the Scripture might stand, that he is the seed only of a woman and not of a man. For the text [Gen. 3:15] clearly states that he will be the seed of woman.

This is thus the first passage in which the mother of this child is described as a virgin. She is his true natural mother; yet she is to conceive and bear supernaturally, by God, without a man, in order that her child may be a distinctive man, without sin, yet having ordinary flesh and blood like other men. This could not have been the case had he been begotten by a man like other men because the flesh is consumed and corrupted by evil lust, so that its natural act of procreation cannot occur without sin. Whatever conceives and bears through an act of the flesh produces also a carnal and sinful fruit. This is why St. Paul says in Ephesians 1 [2:3] that we are all by nature children of wrath” (Luther’s Works, v.45, p.202).

“Christ is promised for the first time soon after Adam’s fall, when God said to the serpent, “I will put enmity between you and the woman, and between your seed and her seed; he shall crush your head, and you shall bruise his heel” [Gen. 3:15]. Here I defer demonstrating that the serpent spoke possessed of the devil, for no dumb beast is so clever that it can utter or comprehend human speech, much less speak or inquire about such exalted matters as the commandment of God, as the serpent does here. Therefore, it must certainly have been a rational, highly intelligent, and mighty spirit which was able to utter human speech, deal so masterfully with God’s commandments, and seize and employ human reason.

Since it is certain that a spirit is something higher than a man, it is also certain that this is an evil spirit and an enemy of God, for it breaks God’s commandment and acts contrary to his will. Therefore, it is undoubtedly the devil. And so the word of God which speaks of crushing the head must refer also to the devil’s head; though not to the exclusion of the natural head of the serpent, for with a single word he speaks of both devil and serpent as of one thing. Therefore, he means both heads. But the devil’s head is that power by which the devil rules, that is, sin and death, by means of which he has brought Adam and all Adam’s descendants under his control” (Luther’s Works, v.45 p. 201-202).