Atheism's declining numbers is based on atheists lack of "fitness," which is short-hand for the fact that women in general don't find the dregs of the science fiction/comic fanboy community attractive.
From the Dallas' Observer's big puff-piece about an atheist convention:
They just don't bring it in very large numbers. At the bar in Austin, some of the male atheists can't wait for more women to show up, probably for the reasons Watson described. Johnny and Ting, both in their late 20s and from Houston, are sitting a little glumly in a corner, several empty glasses in front of them. Johnny is a former Muslim; after he told his parents he was an atheist, his father "didn't speak to me for two years," he says. Ting is a Buddhist. He just came down for a weekend trip with his buddy.Riiiiight, because the nerd community hasn't been saying the same thing for the last 70 years.
"There are no girls here," Johnny says bluntly. "Look at these guys. Would you hang out with them? Do pretty girls want to hang out with these guys? I don't think so." Beyond that, Ting is East Asian and Johnny is Indian; this crowd, Johnny says, "is not our age group, and it's not our demographic."
But he's confident that'll change soon, he says.
"The atheist community, it's not the cool kids yet. But it will be. Right now, it's still a bad word, especially in Texas. What we're doing, we're paving the way for the cool kids to come on board."
He smiles and takes in the room, which is filling up with people. "Ten years from now, this is gonna be really big."
Now, that's some kind of faith.