Source of evil?

Ok I was talking to some religious people and they were telllng me that the evil thoughts and temptations came from Satan. Ok this sounds all fine and dandy but I kept thinking about the story of Satan and how he was an angel at one time and how he was envious of gods power. So he was tempted into leading a revolt against god. Who put the evil thoughts and temptation into Satan's head? Did God do it?