(Disclaimer: As a straight white male, I've never felt the sting of having a mainstream politician call me less-than-human in cleverly veiled terms. I can't imagine...)
Except that I have felt that sting, sort of. One need not look far to find plenty of examples of mainstream politicians demonizing atheists in truly shocking ways. For an admittedly not-that-recent example, look at Bush Sr.'s infamous remarks about whether atheists should even be citizens.
But I can't shake the feeling that it's just not the same. It doesn't cut me as deeply as I think it would to have my race, my sexual orientation, my gender classed as sub-human. And I got to thinking: why is that?
I think it comes down to two major factors: Degree of choice, and "believing" vs. "being".
Now note I said "degree of choice", not "choice". At this point, atheism is not really a choice for me per se. I could no more decide at this moment to believe in god(s) than I suspect you, dear reader, could choose at this very moment to believe in the Keebler Elves. Oh sure, you might freely choose to proclaim an allegiance to Ernie and the gang any time you wish, but you wouldn't sincerely mean it.
But I suspect that if you really dearly wanted to believe in the Elves... If you told yourself every day that they were real, if you surrounded yourself with others who shared the same forthright belief, if you fervently tried to make yourself believe, one day I suspect you'd wake up and be quite certain of the magical origin of Keebler cookies. It might be a more tenuous faith, you might be more inclined to inwardly question it than those who had been Keeblerites since birth or had experienced a more organic conversion to Keeblerism. But I bet if you really wanted, you could pull it off.
To do the same thing in regards to one's race or one's gender is patently absurd. And as we now know from dearly-bought experience, attempting to do so in regard to one's sexual orientation is ineffective, dangerous, and often deadly.
My atheism is something less than a free choice, but it is somewhat more of a choice than are race, gender, sexual preference. I am an atheist because it is what seems to me to be the clear truth. I cannot change it as easily as I could change my shirt or my hair color or the restaurant I go to most often... but I probably could change it with sufficient time and effort, if sufficiently motivated.
The other difference is harder to get at, and I fear I am verging on a form of Cartesian dualism here... But I really think there is a subtle difference between what you are and what you believe.
To explain what I mean, consider a person who is a straight-up communist, and somewhat of an activist at that. If she is really sincere about her communist beliefs, it may be no more of a choice than is my atheism: She could insincerely declare her mind changed at any time, and she may at some time be sincerely argued out of it (and I naively hope she would; I find communism to be about as sensible a position as laissez faire capitalism, i.e. not very -- but this is an irrelevant digression and I will say no more about it), yet if she really believes in her cause at 8:32PM on Wednesday, she cannot simply "decide" not to believe in it at 8:33PM on Wednesday.
And there is no question that many Americans consider communists to be less-than-human. Yet somehow it feels like that stings a lot less than racial prejudice or anti-gay prejudice or misogyny. There's just something about what you think about things, especially when it is ostensibly for rational reasons, that makes criticism of it seem less hurtful than something which you are -- even when the distinction between identity and belief is fuzzy.
Perhaps it doesn't matter that this reeks of dualism; we are all de facto dualists in our day-to-day lives, after all, and since this post is all about perception, perhaps the fact that we usually perceive ourselves as dualists is enough to justify this perception.
In any case, I do think there are differences, and as such I think I still cannot claim to know what it feels like to be a member of a group whose very identity is (or recently has been) denigrated by the mainstream. There are a lot of ways in which anti-atheist prejudice is similar -- there's been much talk about how the "coming out" analogy works very well for atheism as well, for example -- but I think the experience of it is different in some crucial ways.