For some reason on my site I have all these ads about how to find atheists and atheists blogging. To each his own, but I would rather show some other type of ads. Is this possible?
Do not forget, the competitive ad filter is a domain level filter. You cannot filter against keywords. The other way to change the type of ads being displayed is to change the type of content. Since Google AdSense tries to match ads to content, that is the simplest way to avoid those kidns of ads. However, if your site is about religion and the only people paying for religious keywords are atheists -- then you may need to sell ads directly or try out a different ad program.
Did you blog about atheism in a past blog? If so, and the ads are showing now, then Google has a delayed response to your blog. Just continue to blog about something else, and when Google returns, it should send ads for that blog. For people who are experiencing "delayed Google", it usually takes a couple of days for Google to come back.