The following is a comment taken from the book God’s Glory In Salvation Through Judgment, by James M. Hamilton Jr. (Crossway Publishers, 2010). In chapter two of the book the author is commenting on the Torah, and concerning Genesis 3:15 he presents a significant insight on God’s mercy.
Genesis 3:14 & 15
“14 The Lord God said to the serpent, ‘Because you have done this, cursed are you above all livestock and above all beasts of the field; on your belly you shall go, and dust you shall eat all the days of your life. 15 I will put enmity between you and the woman, and between your offspring and her offspring; he shall bruise your head, and you shall bruise his heel.’”
“As salvation comes through judgment, readers of Genesis are given key insights into the nature of God. The promise that the serpent’s head will be crushed comes leavened in the statement of judgment on the serpent. It is important to note that had there been no transgression, there would have been no judgment. Had there been no judgment, there could be no mercy. It would not be needed.
The justice of God is put on display as he judges the serpent. The mercy of God is demonstrated as he announces – from no compulsion or constraint – a future salvation that humanity has neither merited nor requested. God freely declares that the seed of the woman will crush the head of the seed of the serpent, and in this salvation that comes through judgment – judgment that results from the human transgression and promises final justice on the evil of the serpent – comes the first picture of free mercy in the Bible. Adam and Eve are responsible for their actions. They are guilty. They deserve death. God does not owe them mercy, and they have only sought to avoid justice by shifting blame (Gen. 3:10 – 13). They are not seeking God; they are hiding from him (3:8). They do not ask for mercy; they do not take responsibility for what they have done. Even if they ask for mercy, God is under no obligation to grant it.
This mercy, then, arises only from God. This is not something that humans deserve, not even in part. Of his own goodness, displaying his own intrinsic character, God announces that the woman will have seed – which means that the promised punishment of death will not be immediately enacted on the physical bodies of the human couple. Not only will their physical lives continue, but they will have seed: offspring. Not only will they have seed, but their seed will triumph over the snake. Salvation comes through judgment, and God makes known his character in justice and mercy. His justice is as exacting as his mercy is surprising.”