Finally, the promise of Genesis 3:15 has implications for Christians’ personal lives of holiness and sanctification because in that verse the gracious enmity between God’s people and sin is seen to be one of the greatest gifts God has given to His people. Often, this is counterintuitive. For a Christian, having to struggle with sin often is seen to be bad. But Genesis 3:15 makes clear that there ought to be enmity between God’s people and sin. If there is no enmity, it is not because there is no sin around the individual or in the individual. There is no enmity because there is no enmity. And if there is no enmity, there is little evidence of a gracious work in the heart of that individual. When a woman’s enmity against sin appears to diminish and her struggle with sin abates and she seems to be at peace, it is precisely then that there is cause for grave concern. God’s people from Eden to the consummation are marked by, and torn by, enmity against the evil one and all of his ways.

STEPHEN G. MYERS, GOD TO US – COVENANT THEOLOGY IN SCRIPTURE, 187.