Cain

In the game Cain is portrayed as murderous for the fact that he wants the Piece of Eden, the Apple, that Adam had had, and obviously passed down to Able.  Cain killed his brother for the power and anything that refers to Satan must have to do with bad aspects of the power of the Apple...and Cain became Mahan, the master of the secret of knowing the truth of Those Who Came Before.  The Mark of Cain is on his neck, and it is the equal sided cross that the Knights Templar order uses.