Should I tell my girlfriend that I'm an atheist?

[Der/die AtheistIn]

Okay she's not really my girlfriend we're just kind of talking right now. But I found out that she does go to church and so she is most likely a Christian. I really do like this girl and I want to make it work with her, but she does not know that I'm an atheist. As a true atheist, I stand behind my beliefs 100%. But when it comes to women, that 100% turns into about 23%.

I don't think that admitting my atheism to her will sway her intentions towards me. I'm more likely to screw that up on my own. But none the less I am trying to present an image from the core of my being that is nothing more than myself. I keep it real. So I want to tell her that I don't believe in her God (though not exactly in those words LOL). Should I just make the announcement plain bold and simple? Or should I just wait until it kind of falls into place? Opinions atheists. I trust your feedback more than I've ever trusted the Christians, even if you guys have more sarcasm behind your rhetorics.

First try to find out if she is a devouted believer, someone who practices religion just for comfort or something in the middle. I recommend you not to ask her directly that, but instead tell her about people of different faiths and see how she reacts. Try to find out what she thinks about atheists before telling her that you're atheist.
It's also very important to see if she fits you regarding other things than religion.