Nobody knows. You can choose it when you play the game, but it has never been defined in the canon (not even in the new book that tells what happened to him, or so I've heard).
"Grant Allen [...] had written a book about the Evolution of the Idea of God. [...] it would be much more interesting if God wrote a book about the evolution of the idea of Grant Allen." ~ G. K. Chesterton, The Everlasting Man