Satan was successful in breaking the fellowship between God and man. But rather than destroy His enemy immediately, God spoke a promise. It echoed with the cries of warfare, and ended with the sound of victory. At that moment, God's words of hope set in motion the greatest plan of all time.
“And I will put enmity between you and the woman, and between your seed and her Seed; He shall bruise your head, and you shall bruise His heel.” (Genesis 3:15, NKJV)
Since the fall of mankind, those who seek after God are constantly forced to charge their way through enemy lines to get to Him. And once they do, they have to continue fight to keep their positions. Every day of a Christian's life is a battle against the enemy of their soul. Satan hates God, and hates God's people even more. His only mission in this life is to steal, kill and destroy. He is fully committed to do whatever he can to prevent people from turning to God.
But God did not leave His people defenseless. Nor did He sentence them to fight against Satan for eternity. The Promised Seed of Genesis 3:15 became the Messiah for whom the entire world waited for generations. This Messiah, who was the Son of God, came as a man to snatch back all of mankind from the clutches of the enemy. “For this purpose the Son of God was manifested, that He might destroy the works of the devil.” (I John 3:8)
When the Son of God breathed His last at the crucifixion, all of Satan's forces believed they had finally conquered their greatest enemy. But just as God had promised from the beginning, Satan only “bruised His heel.” It was at His resurrection that Jesus Christ took back from Satan the keys to death and the grave, and reclaimed all power and dominion that Adam had handed to Satan at the time that sin was first introduced into the world. While this loss may have only crippled Satan for a time, one day he will be the one completely destroyed, never to rise again. “Inasmuch then as the children have partaken of flesh and blood, He Himself likewise shared in the same, that through death He might destroy him who had the power of death, that is, the devil.” (Hebrews 2:14)
The passage in Genesis 3:15 is the first of many prophetic messages about Jesus Christ, the Son of God. No mere man could fulfill God's plan of redemption. And no mere act of man could free those who were slaves to sin and death. Only the sacrificial blood of Jesus could render ineffective the works of the enemy. And only through the Person of Jesus Christ could Satan be completely and permanently trampled underfoot.