You find out some one you know is a flaming, bone-headed racist. How to explain it? An intelligent person. One who has never actually had personal experience with people they feel "superior" to.
Baffling. Really.
I mean, I know we all have some in-built bias, probably encoded inside us. Is it true that racism is "hard-wired in our brains?" Then none of us are exempt. But it is something we can recognize and work against. It is essential. To find empathy for our fellow beings.
Celebrate and honor the differences between us. Maybe idealistic. But it's the only way.
This deep hatred of people because of their "race" is just so confounding. Not something understandable. Sad. Hard to explain. Ugly.