Margaret Rhatican refered to the snake in genesis as the devil, using information from her new testament. It is important to keep seperate the original texts and stories with which we are currently dealing and the way they were interpreted and used later. In Genesis, the snake is not the devil, it is merely temptation. Those are seperate. While temptation was later associated with the devil, the devil was not invented until much later when they needed him to counter other religions like the Roman religion. thus the devils Pseidon "pitchfork" and Pan-like fawn horns and feet. Well, with that image of him at least.

Religion is a tangled web of imagery and political statements. Remember to deal with the imediate text at hand.