To another of QP's (NSFW site) posts:
(I put them here where I think my comments are controversial enough among her other readers to invite a flame war, incidentally, which is why they show up here rather than in her comments.)
I'd omit religion and political affiliation from that list, for the simple reason that religion and political affiliation are more philosophy than not, and philosophy is a legitimate domain for prejudice. (For example, you express a philosophic prejudice against prejudiced philosophies here, something I think you will agree is legitimate.)
Even when religion and political affiliation aren't directly philosophic they are indirectly, because the decision not to analyze your belief system is a philosophic one.
Religion and political beliefs are to a great extent the odd man out in prejudice, partly because they are a matter of choice (unlike most targets of prejudice), partly because they've been the source of so much prejudice, and partly because they've been the domain of more violent and invalid prejudice than anything else - so we have very good reason to be wary of prejudice against these two things even as they're the two things which most lend themselves to valid prejudices.
It's possible for a religion or political group to be totally irredeemable, after all, in any self-consistent moral code which forbids prejudice. (As they might include prejudice as tenants.)
Which is not to say an individual belonging to such a religion or political belief system can't buck the system and be a good and moral person, but as with slavery and kind slave owners, these individuals may be the worst moral offenders by lending their support and credibility to a morally corrupt system.