If God is all-powerful, why hasn't He killed Satan? This question deserves careful attention, since removing Satan before he tempted Eve in the Garden of Eden may have kept sin from entering the world.
God vs. Satan? If He is really all-powerful, why doesn't God just kill Satan?
First, we must acknowledge God is all-powerful and could destroy Satan if He desired. Since He has not destroyed Satan, there must be some reason for his existence that ultimately serves as part of God's perfect plan for humanity. We have to remember that simply because God can do something does not mean God has to do it. And, that simply because God doesn't do things our way doesn't mean He's wrong.
Second, the possibility of sin must exist to allow humanity to have free will. Free will is required for the existence of genuine choices, including the choice to love God. Even if Satan had not existed, we would still have had free will and the opportunity to commit sin. As it turns out, sin entered through Adam and Eve, aided by the actions of Satan. But this doesn't mean sin could never have entered some other way.
Third, Satan's existence also serves as part of God's redemptive plan through Jesus Christ. When Jesus came to earth, He was tempted by Satan (Matthew 4:1–11). Satan worked in the life of Judas Iscariot so he would betray Jesus, leading to His sacrificial death on the cross on the behalf of the sins of humanity. Even though Satan's intentions are evil, God is able to use them in order to further His will.
This is a great example of Romans 8:28, which teaches, "And we know that for those who love God all things work together for good, for those who are called according to his purpose." In addition, other works of God have shown this to be true as well. When Joseph's brothers sought forgiveness for selling him into slavery, Joseph replied, "As for you, you meant evil against me, but God meant it for good, to bring it about that many people should be kept alive, as they are today" (Genesis 50:20). Jonah was swallowed by a great fish (Jonah 1), yet God used this event to help save a city from judgment.
Fourth, God has already revealed His plan to ultimately defeat Satan. Revelation 20:10 states, "the devil who had deceived them was thrown into the lake of fire and sulfur where the beast and the false prophet were, and they will be tormented day and night forever and ever." Satan will be removed from God's people, punished forever.
This is a key point, often missed when looking at the "God vs. Satan" conflict. In a sense, Satan is already defeated. Deer that are shot by hunters often run hundreds of yards before they die, even though the bullet wound is fatal. Like an animal that's been shot, but hasn't actually died yet, evil has been fatally injured by God. We're just waiting for everything to settle into place. When that happens, all wrongs will be made right, and all evil will be punished.
We rightfully wish Satan no longer worked his evil in this world. However, God has a plan that will ultimately end Satan's work. For now, we can view Satan's operations in this world as an opportunity to depend on the power of God's Spirit to resist temptation, fight injustice and evil, and to stand strong in sharing Christ's love with those who have yet to believe. God will determine the timing of Satan's judgment as He wills; we are called to follow God's plans while resisting the evil efforts of the devil.
Is God omnipotent? What does it mean to be omnipotent?
Who is Satan?
How is it that Satan thought he could defeat God?
Why did God allow the Satan and the demons to sin?
If God knew the Fall was going to happen – that Satan would rebel and Adam and Eve would sin – why did He create them?
Truth about Angels