Is anyone going to Comic-Con? You've probably heard that the Phelps gang will be picketing it (IMPORTANT: you know Phelps is a litigious con-man who baits people so he can sue them, right?), so you may have to pick a god to annoy them. Here's a list of appropriate comic book gods and goddesses. Praise Thor, piss off Phelps.
Although I would think being an atheist would be even more effective. For that, here's a list of atheist comic book characters. It's short, and unfortunately, most of them aren't very memorable.
There is, apparently, a comic book called The Atheist. I've never seen it, but it sounds…interesting.
The storyline revolves around present day humans that are having their bodies being "possessed" by the souls from Hell similar to the possessions in the fifties horror movie "The Invasion of the Body Snatchers". The souls from Hell then begin an extremely hedonistic and malicious lifestyle that includes raves, drugs, self mutilation, murder, and other violence. The possessed bodies then start congregating in Winnipeg, Canada.
That's not very atheistic. But, yeah, it sounds exactly like Winnipeg.