Per the wiki, I grew up in a neighborhood that was 95.1% white. I was well into my teens before I actually came to be good friends with someone who was not a white, middle-class Christian person. Even so, I persisted with the thought that discrimination was not a problem. That those who complained were playing the race-card or acting as the victim, or that liberals were just being whiny when they talked about 'privilege'. I was never given the opportunity to understand that I was afforded huge benefit in American society, in that I never had to give thought to my race, religion, gender, etc.
In addition being the more fringe libertarian back then, I had the very stupid idea that people were entirely empowered to do whatever they wished. That as the quote above contends, offenders have a right to discriminate because people are afforded recourse when they face explicit or implicit discrimination. It was only after I spent time overseas, became good friends with people of different minority groups and had several gay slurs hurled my way that I actually "got it". It's one thing to say, "Christians have the right to refuse service!" than to actually be the one who is hurled out of the restaurant with ill-intent not just once, but multiple times. It's a rude awakening that changes your world view very quickly.
Of course, having once held these beliefs that discrimination is not a problem ... I can very easily recognize it in other people. My frustration now is trying to drag these people into "getting it" as well. How does one do that with a person, who does not have the potential of experience discrimination him/herself?