Though on an interesting note: the Bible notes that Satan has power over the world.
I contend that power is limited to his minions, and the living he gains power over. I believe no God with the power of light and truth, and the means to provide for his children, would give to another the power to destroy his purpose or the means to achieve it.
Satan can wage war on the God of Israel, and gather a flock, but in the end, neither he nor his subjects, nor any of God’s children, have the power to destroy his creations or purpose. The souls of men are at stake, and the Son of God, has provided the atonement as our path to salvation, the battle goes on for a time, but in the end...
This is turning into a philosophical debate. While I agree that in the end Satan & the forces of evil will be defeated the fact of the matter is that they sure do still have quite a strong hold on the world as all one has to do is look around at how brutal this world tends to work.