Why is it, in fact, that we should have a devil? Why did not the Lord kill him long ago? Because he could not do without him. He needed the devil and a great many of those who do his bidding just to keep men straight, that we may learn to place our dependence on God, and trust in Him, and to observe his laws and keep his commandments.John Taylor, 3rd President of the LDS, 29 October 1882, Journal of Discourses 23:336.
So let me get this straight. Our omnipotent God does not have the power to “keep men straight,” so he needed the devil to do it for Him?!? This is certainly NOT the God of the Bible.