We're getting a bit stuck on definitions of 'atheism' here. Is it just lacking a belief in God/s or is it believing that there are definitely no Gods. Even though it's often made out to be the latter, I doubt that's really what most atheists would define themselves as. God, by definition something that can't be proven or dis-proven. It's a concept, that either works with a persons mind-set or it doesn't. That mind-set can change of course, depending on experience, but some people will always be more inclined to the concept than others. It should follow then that any discrimination based on receptivity to this abstract concept would be quite unfair. But the question was, do Atheists face discrimination? Well, of course they do. Who can deny that. Just as theists face discrimination as well; but in different contexts. From an outsiders perspective, the US especially seems to have a very strong attachment to the notion of God, seemingly regardless of any particular modern reasoning I'm aware of. I gather it's just something ingrained in society. It's a whole different topic whether that's good or not, but I don't think you can deny that it exists and where it's particularly prevalent there will be discrimination against those who don't believe.
[as a sort of side note]: Rob, you were starting to hit on some interesting ground there about why people believe. I'd say It has a lot to do with explanation. It comes down to whether you're the kind of person whose prepared to say "I don't know the answer" or do you need to find an answer that will fill that void. The later option definitely offers welcome peace-of-mind and a certain steadfastness....though, that isn't an option I'm able to accept. For one reason or another, I'm quite happy just being open to possibility...or being open to whatever is the best explanation of what is presented to me, in life. And indeed, in regards to these spiritual questions, it's doubtful you'll ever find another persons answer that will completely agree with all your logic & experience. In my mind, the best thing to do then is to formulate your own hypothesis, irregardless of what other people think (something I think you were getting at). Some self-constructed set of beliefs, which by their very nature you don't have to compromise on (as you might have to when conforming to a religion). It just seems that as soon as you decide that one answer is correct for everyone or correct for all time I think you've given up something. You've gained a bit of satisfaction for sure....but you've also given up a curiosity, that I think is quite important, even though I'm exactly not sure why.