Well, I fit the definition of atheist, and I post here, so... I suppose this question is directed at me as well. Before I moved to Montreal just over a year ago, I owned one copy of the Bible, NIV, it had lots of notes and bookmarks in it
I've personally read the majority of the Bible, and if I need to see something now I can just look it up online. However I left that personal Bible back at what used to be my home, by the way what used to be my home had at least 5 different Bibles, my parents were intense. (A lot of atheists are ex-Christians)
As for atheists being banned, I can't say for sure but it seems as though those who are respectful and civil aren't having a problem. I haven't received any ban warnings before, even through passionately arguing my secular stance on some controversial issues. Just always refrain from personal attack or being condescending in any way, I think that works. Thomas also doesn't seem have any trouble here and I haven't seen anything that could be taken as offensive in his posts.