When the armies of the world have been destroyed and the Anti-Christ thrown into the lake of fire, Christ will have Satan, the Devil bound in a bottomless pit for a period of time. The pit whether spiritual or physical will mean his influence on the world will be over, at least for that period of incarceration. The reason for this is that God is moving into another phase of his plan for mankind and he doesn't want evil to be a part of this new age. The Devil's freedom is not yet at a permanent end but the time to come while he is out of the picture will be one of peace and harmony. Most of the violence in the world is due to his influence on humanity and mans falling to temptation from him. With Satan out of the way man can enjoy a life similar to what God had intended from the beginning. But, and it is a big but, it is only for a period of time, not forever.