Atheists and Adiabolists

There are those who believe in the literal existence of both God and the Devil, of course. And of course there are atheists who are also adiabolists. There are even some who, motivated by a committment to a God of perfect Love, believe in God but not in the Devil. What I'm interested in is whether there are any people who believe in the Devil but not God? Given the enormous diversity of peoples' beliefs, I'd be surprised if there weren't; but how would such a belief-system pan out?