God spoke of Satan’s defeat in Genesis 3 when the seed of woman (Christ) would crush the head of the Serpent. It reads, “And I will put enmity between you and the woman, and between your seed and her seed; He shall bruise you on the head, and you shall bruise him on the heel (Genesis 3:15).
The Old Testament prophets provide more details concerning the “bruising of the heel” of Satan’s destroyer.
Our Lord spoke of Satan’s defeat during His earthly ministry, especially as the time of His death drew near: “Depart from Me, accursed ones, into the eternal fire which has been prepared for the devil and his angels” (Matthew 25:41). Again, He explains, ““And concerning judgment, because the ruler of this world has been judged” (John 16:11).
The apostles likewise spoke of Satan’s doom, seeing it as accomplished through the death of Christ, but still to be fully carried out at His return, which was in the future of the writings but imminent and soon approaching. Paul writes to Roman saints, “And the God of peace will soon crush Satan under your feet. The grace of our Lord Jesus be with you (Romans 16:20). John writes, “The Son of God appeared for this purpose, that He might destroy the works of the devil (1 John 3:8). Christ has bound the “strong man” and took his spoils. Now, Jesus has the keys of death and hades. Satan is bound during Christ’s reign with His saints, and it is only a short time, relatively speaking, that Satan has to unleash his work of deception on the earth before God sends fire from heaven when he shall once and for all put an end to Satan’s work. There will be no need for keys to death and hades at that time as they will no longer exist. Both they and Satan will be forever cast into the abyss where they will be tormented forever.