Dr. King once famously said he dreamed of a day when a man was judged not by the color of his skin but by the content of his character.
Speaking for myself, I can't remember a time when I "judged" a person by the color of his skin upon first meeting the person. Of course, sometimes the person's character becomes evident the minute they open their mouth and speak, or when you read the writing on his T-shirt, but I have never said to myself, "Here comes a black man. I know what he's going to be like."
Of course, I grew up in the north and MLK experienced what he experienced in the south and formed his opinions about white people and black oppression from his own experiences there. He was right. On the other hand, just because blacks living in the north in the late 1950s or early 1960s didn't have the police set dogs on them or get sprayed with high pressure fire hoses when they tried to eat at the Woolworth lunch counter didn't mean they didn't suffer humiliating treatment or otherwise experience racism. Surely, sometimes the "quiet racism" of smiling white liberal Christians must be nearly as exasperating as police dogs. That's just my personal observation; I don't have any way of knowing for sure.
So, I ask myself where "prejudice" started in the first place. Way back at the beginning of mankind, was there racial conflict back then? Because it sure doesn't seem like it started in recent history. If this weird desire to not be around each other (it probably works both ways) DOES go back for thousands or tens of thousands of years, then maybe it had its roots in some sort of instincts back then. Just speculating.
What if humans have ALWAYS had this uneasiness inside them that made them be wary of ANYTHING new, anything different than themselves. A survival mechanism. Whatever. At the very root of it all, isn't that what "discrimination" or (insert your own hate-word here) is defined as? "You are different than I am. Let me slowly and carefully check you out and see if you mean to hurt me or not."
It's a good instinct to have if you meet a bear or a lion. Perhaps it's good to be a bit wary when you meet a new person, too. Especially if that person in some way looks different than you. Maybe that's why little children when they are "shy" take a while to warm up to a stranger and make sure there is no danger before they get too friendly. In today's world, good for them.
But, after being around another group of people for hundreds and hundreds of years, it would seem only natural that you would not be wary anymore. Not at first, at least. There is obviously much more than initial instinct at work here. Modern racism is obviously (to me) learned behavior.