Genesis 3 and 4 serve as an introduction to the book of Genesis as well as the rest of Scripture. Throughout the book of Genesis we read stories where the antithesis between the seed of the serpent and the seed of the woman plays itself out. This is the story of Cain and Abel. There is certainly much to be gleaned from this story, but one important principle is the antithesis that already shows up in Adamís family. Sin brings enmity, and Cain kills Abel. But how will the seed continue? Will Godís promise become void? Abel seemed so faithful. But God is faithful and he gives Seth to Eve, giving her a younger son who will be blessed and will carry on the blessing of God instead of the older.
Interestingly, this theme does not end here. The theme of struggle between older and younger brothers continues. Cain, Abel, and Seth; Shem, Ham, and Japheth; Ishmael and Isaac; Esau and Jacob; Joseph and his eleven brothers; Ephraim and Manasseh are all stories of the triumph and blessing of the younger brother. The antithesis is between offspring. There is enmity in the family line, but God continues to prove his promise sure by raising up younger brothers. There is story after story of the victory of the younger over the older and salvation from the younger brother. What does this mean?
If we think back on the fall, having outlined the rest of the book of Genesis as a complex collection of stories about the need for a faithful descendent and the struggle between younger and older brothers, we realize that there is something missing. God gave Seth to carry on the blessing when Cain murdered Abel. God raised up Jacob when it was clear that Esau would not be the bearer of Godís covenant blessing and promise. God gave Joseph to Jacobís house when there was a famine, raising him to the highest place in the kingdom of Egypt. Having read all these stories (and the others) we ought to reach the end of the book of Genesis and realize that Adam needs a younger brother. These other younger brothers are small pictures, but there needs to be younger brother to Adam, a man who can stand in our place, like Adam, a man who could keep the covenant that Adam broke. But alas, Adam has no siblings.
If we read the rest of the Genesis we see salvation coming from younger brothers and our immediate thought should be: If only Adam had a younger brother! And we would have to realize that this younger brother would have to be like Adam, having God for a father, because a physical father would carry Adamís curse. But the man couldnít be simply made from the ground again, because it too is cursed. Therefore, keeping his promise, God determined to bring forth Adamís younger brother from the womb of a virgin. The Holy Spirit “overshadows” Mary, as He had once done in the beginnning, and brings forth a new man. Adamís younger brother is the Lord Jesus Christ who was conceived like Adam without a natural father. In the mystery of God, the seed of the Woman is Adamís little brother. Mary, in a glorious way, is the new ground from which the new Adam was formed. This is the glory of God and the wonder of Christmas that God not only created a new man, a brother for Adam, but that God himself became this man for us, God gave himself to be Adamís younger brother, the seed of the woman who would bruise the head of the serpent.