^
if that's a legitimate question, the beginning to the answer is... some people do that, yes, but it's not common. It's worth asking "which god" someone believes in, or what is their theology, etc. The ancient greek pantheon had many gods and a "devil" figure, but not quite the same as the judeo-christian conception. For the norse gods, Loki is a trickster, but I'm not sure if he's a "devil" or not. Creedal Christians don't teach that God and the devil are equal-and-opposites of one another. That'd be more like ... I dunno.... Eastern philosophy halfway mixed with Judeo-Christian themes.
TL;DR:
no because:
http://webdiplomacy.net/profile.php?
userID=31362 and
http://webdiplomacy.net/profile.php?
userID=6927