I heard someone ask why God doesn't just destroy Satan NOW the other day. Interestingly, they asked this while buying liquor, cigarettes and a stack of lottery tickets. I'm not passing judgment on this person (not only because I'm just as bad in my own ways, but because this turned out to be a very decent and introspective person), but do you see the problem here?
God gave Adam a perfectly simple chance to get rid of Satan once and for all in the Garden of Eden by advising him to eat of every tree in the garden except for the Tree of the Knowledge of Good and Evil. If he would have followed this advice, he would have eventually eaten from the Tree of Life and gained eternal life. Instead, however, he fell for Satan's lie that eating the forbidden fruit would make him into a god. God told Adam that things were going to be different after that. Mainly, man's peace of mind was only going to come after great toil and discipline until the Redeemer, Jesus, made everything new again (Genesis 3:17-24). Through Paul the Apostle, God told us that until things are made new, we are going to reap what we sow (Galatians 6:7). Like I said, I'm not passing judgment on this person who was standing there with liquor, cigarettes and a stack of lottery tickets while asking why Satan holds such sway over us, but hopefully this helps someone to see why he does. We reap what we sow. And when we sow Satan, we reap Satan, and his influence continues on in our lives.