Unexpected discovery of the bad kind

I don't know how it happened but amazingly and despite the general right-wing nutjob catholic trends in my homeland I managed to grow up in a liberal environment. It turns out I've been surrounded with stinky liberals starting with my parents and their closest friends, all through my close friends in school, high school and then uni. Of course this optimal caring and understanding upbringing meant I ended up assuming that none of the people I met and liked could turn out sexist, racist or homophobic. So it came as quite a shock when last week one of my friends at work said he'd prefer not to serve a group of black customers because they will just cause him trouble. At first I thought it was a bad joke (especially considering the said "friend" was of an ethnic minority himself), but no. He reiterated. I said he was being racist. He took offence to that, saying basically that because it was him who had the problem with serving them it wasn't racist (I know! wtf?). I responded that without having met the individuals and basing his judgement and decision not to serve them solely on the color of their skin he was in fact fitting right there into the definition of the word. He disagreed and I'm pretty sure he still bears a grudge against me for smearing his name with the "r" word.
Me - I'm confused. Is my friend racist despite denying thinking that he is somehow superior to black people in any way? And if he is racist is he still my friend? How do I draw the line between opinion, stereotype and racism in what other people say? I mean if I was in doubt over a newly met person I'd just stay away, but what if it's somebody I already like and respect? Hmmm...
Another example is from another friend who said he doesn't hate gay people, just the idea of being gay. Which to me sounds like a closeted homophobe convinced that he isn't one. What can I say to that? Is it possible that the real message here is "I tolerate but not accept gay people"? For the moment I feel betrayed. Not sure what to do now.
Suggestions anyone?