Research more about his style and approach. He goes to great lengths to understand their views before meeting them. In his AMA he mentioned that he would even hold debates with himself in the mirror, representing his own opponent. Extraordinary stuff.
That's great, but I agree with the OP - I expected, given the headline, to find out why the Klansmen hated him. But the article doesn't actually say. In fact it doesn't give a voice to the Klansmen at all. It just says: I went and talked to them and they became friends. Eventually they changed and gave me their robes.
Nice story and I'm sure it's true. But it didn't help me understand the KKK any better, which is a shame.
As far as I can tell, the point is that there was NO actual reason why they hated him apart from they didn't know him. Once they knew him, they didn't hate him.
The ones that changed their point of view, eventually just realised they had no remaining reason to hate him. And by extension it was irrational to automatically hate every other black person they didn't know yet.
It was his attempts to understand them, that helped some of them understand him. As he points out though, there were plenty of klan members that this didn't work out with though.
It obviously takes some level of self awareness/reflection to change your mind like that.
