God was identifying two spiritual genealogical lines from that point. There would be a godly line of men, and a satanic line. The godly line would lead to Christ. The satanic line would lead eventually to the Roman Empire which was Satans earthly empire in competition with God for the souls of mankind. The first satanic human was Cain who murdered his brother Abel. And the godly line progressed through Seth, an early ancestor of Jesus.
In your passage, the seed of the woman is Jesus, born through Mary, and then the Christian church. The seed of the serpent through Cain to Rome who crucified Jesus, martyred the apostles, and persecuted the early church.
Satan the serpent struck Jesus' heel, the crucifixion, and Jesus bruised Satans head, meaning his power and authority.
Now campare the seed of the woman in Gen 3.15 with this passage....
Revelation 12:17 KJV — And the dragon was wroth with the woman, and went to make war with the remnant of her seed, which keep the commandments of God, and have the testimony of Jesus Christ.
Dragon is Satan and his empire of Rome. Christ was born under Augustus and died under Tiberius, all satanic men.
Remnant of the womans seed is the small remnant Christian church.
Its always been about Satan and his people versus God and his people. God wins. Satan loses
Best question here ever. Thanks for letting me explain it.
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- The woman: she represents the heavenly people of God, composed of angels in heaven: "Then a great sign was seen in heaven: A woman was arrayed with the sun, and the moon was beneath her feet, and on her head was a crown of 12 stars" (Revelation 12: 1). This woman is described as the "Jerusalem above": "But the Jerusalem above is free, and she is our mother" (Galatians 4:26). She is described as the "heavenly Jerusalem": "But you have approached a Mount Zion and a city of the living God, heavenly Jerusalem, and myriads of angels" (Hebrews 12:22). For millennia, in the image of Sarah, Abraham's wife, this heavenly woman was sterile, childless (regarding the mentioned offspring of Genesis 3:15): "Shout joyfully, you barren woman who has not given birth! Become cheerful and cry out for joy, you who never had birth pains, for the sons of the desolate one are more numerous than the sons of the woman with a husband,” says Jehovah" (Isaiah 54: 1). This prophecy announces that this sterile woman will give birth to many children (King Jesus Christ and 144000 kings and priests).
- The offspring of the woman: The book of the Apocalypse reveals who this son: "Then a great sign was seen in heaven: A woman was arrayed with the sun, and the moon was beneath her feet, and on her head was a crown of 12 stars, and she was pregnant. And she was crying out in her pains and in her agony to give birth. (...) And she gave birth to a son, a male, who is to shepherd all the nations with an iron rod. And her child was snatched away to God and to his throne" (Revelation 12: 1,2,5). This son who will "shepherd all the nations with an iron rod" was designated by the angel Gabriel as Jesus Christ: "This one will be great and will be called Son of the Most High, and Jehovah God will give him the throne of David his father, and he will rule as King over the house of Jacob forever, and there will be no end to his Kingdom" (Luke 1: 32,33). Nevertheless, the child whose heavenly wife gives birth refers to the Kingdom of God, whose Jehovah anointed his Son Jesus Christ as King (Psalms 2).
- The original serpent is Satan the devil: "So down the great dragon was hurled, the original serpent, the one called Devil and Satan, who is misleading the entire inhabited earth; he was hurled down to the earth, and his angels were hurled down with him" (Revelation 12:9).
- The offspring of the original serpent represents the heavenly (demons or angels of the devil) and earthly enemies of the Kingdom of God, those who actively fight against the sovereignty of God and against King Jesus Christ and the holy ones on earth: "Serpents, offspring of vipers, how will you flee from the judgment of Gehenna? For this reason, I am sending to you prophets and wise men and public instructors. Some of them you will kill and execute on stakes, and some of them you will scourge in your synagogues and persecute from city to city, so that there may come upon you all the righteous blood spilled on earth, from the blood of righteous Abel to the blood of Zechariah son of Barachiah, whom you murdered between the sanctuary and the altar" (Matthew 23: 33-35).
- The wound of the heel represents the sacrificial death on earth, of the Son of God, Jesus Christ: "More than that, when he came as a man, he humbled himself and became obedient to the point of death, yes, death on a torture stake" (Philippians 2:8). Nevertheless, this wound on the heel has been healed by the resurrection of Jesus Christ: "Whereas you killed the Chief Agent of life. But God raised him up from the dead, of which fact we are witnesses" (Acts 3:15).
- The crushing of the serpent's head means the eternal destruction of Satan the devil and demons and the earthly enemies of the Kingdom of God, at the end of the thousand years of the reign of Jesus Christ: "For his part, the God who gives peace will crush Satan under your feet shortly" (Romans 16:20). "And the Devil who was misleading them was hurled into the lake of fire and sulfur, where both the wild beast and the false prophet already were; and they will be tormented day and night forever and ever" (Revelation 20:10).