OK, here’s a former Klansman Thomas Martinez on how he was converted by David Duke (Brotherhood of Murder, pp. 20ff.):

It was in that frame of mind that, a month or so later, I happened to turn on Tom Snyder the night David Duke was interviewed. Duke was a young man—only a few years older than me—and ruggedly handsome, looking like a young Robert Redford in the way Bob Mathews looked like a macho version of Donny Osmond. As Duke was talking of how the government had money to bus black kids to school but not a penny for the working-class white man, I thought: “Damn, this guy is right. This guy is right! Who is this guy?”
He was, he told Snyder, the Grand Wizard of the Ku Klux Klan. In school I’d learned that Klansmen were vigilantes, an image that was favorable to me from the cowboy movies I had seen at the Midway Theatre when I was a child. I also knew, whether from school or elsewhere, that they wore robes and hoods, took secret oaths, had secret rites, which meant to me that they possessed a secret knowledge. That attracted me, and so did Duke, so smooth and articulate; and when he told Snyder he had an IQ of 173, I thought: A person that bright has to know what he is talking about.
The following day I called the television network and was connected with a member of Snyder’s staff, who readily gave me Duke’s address in Metairie, Louisiana. I wrote him immediately, asking for information. By return mail he sent me his magazine, The Crusader. It was nicely packaged, containing none of the ranting about “kikes” and “n*****s” that are the common coin of most racist publications. Rather, the articles focused on my pet bugaboos, affirmative action and busing. It met my needs. It explained why I wasn’t getting any where. I had been right all along. It wasn’t my fault.
I sent him a check. About a week later I called him, asking for more literature. He sent it, along with an application. By then I was in a state of awe that someone so important, who’d been on national television, would take the time to speak to me. I filled out the application and mailed it, and that was all there was to it. I was now a full-fledged Knight of the Ku Klux Klan.