Well /r/atheism is one of the most hated subreddits on reddit. There is not much discussion but rather a fair amount of deity mocking along with few submissions worthy of discussion (check /r/trueatheism for discussions). These days >80% of submitted content are images that mock religion in some way.
OP, is /r/christianity blocked? Is /r/exmuslim blocked?
I've read many posts where people said "they needed those pesky comics" to point out to them how silly it all really is.
I'm personally not a fan of it, except for maybe the philosoraptor memes. short, to the point, and makes sense (99% of the time)
Thanks for the link to /r/trueatheism though, i'll check it out as that is what tickles my fancy.