Why did God allow Satan to live and do what he does? Why didn't God destroy Satan? Would that not have stopped a lot of sin?
God has not told us why He allows Satan to live. It appears that God allows every creature that He has created to live eternally. The real question is, “Why does God allow Satan to roam the earth and cause trouble?” God has not shared the answer to that question either.
Satan & Sin
We do not need Satan to sin. He is not the cause of sin. He tempts us to sin, but God tells us that we do a great job of sinning all on our own. In the book of James, the Holy Spirit says,
But each one is tempted when he is carried away and enticed by his own lust. Then when lust has conceived, it gives birth to sin; and when sin is accomplished, it brings forth death. (NASB) James 1:14-15
We are responsible for our own sin. We sin after we think about it and then decide it is a good idea. Satan is never blamed for our sin. Does that mean that Adam and Eve would have sinned without Satan? We do not know.
Satan Defeated & Released
At the end of the age, God will defeat Satan at Armageddon. He will be thrown into the abyss which will be shut and sealed. He will be locked up. God will set up His 1,000 year kingdom and after that He will release Satan again. In fact, scripture says that God must release Satan for a short time (Rev. 16:16; 19:11-20:3),
. . .and threw him into the abyss, and shut it and sealed it over him, so that he should not deceive the nations any longer, until the thousand years were completed; after these things he must be released for a short time. (NASB) Revelation 20:3
Satan will be released in Revelation 20:7-10 and then defeated once more before his final and eternal sentence to the Lake of Fire. Why did God do that? We can only guess. It is possible that God wants to show the fallen angels (demons) and the human race, that even after they have experienced the holiness of God, they will choose sin and rebel when given the opportunity. God will be justified in sentencing them to eternal punishment. It will show the sinfulness of man and the holiness of God. This is the nature of man. We are evil creatures at heart without the transforming power of the Holy Spirit.
Why did God allow Satan to live? We do not know, but we can rejoice that by trusting in Jesus for the forgiveness of or sins, we can live in holiness someday with Him – away from the evil of this world and eternal punishment.