Once upon a time a Savior came to save the world from itself. His cause was righteous and his methods were ruthless. Perfection beckoned, the end justified the means, and resistance was futile.
Soon all men bowed down to him, willingly or not; but every angel that he commanded became a devil, and every devil that he battled became an angel. He soon learned how to speak and think like those whom he had overthrown.
In the end it was the Savior, and not the world, who was destroyed in order to be saved.
Moral: Turnabout is fair play.