I find it easiest to say nothing, and to keep my inner thoughts hidden. "No thank you, I'm not interested" works pretty damn good in almost every situation, and people wear themselves out pretty quickly as they try to pry more information from you but are unable to get more than that. And remember, you serve yourself! Satan as he exists in my mind (me) doesn't give a shit if I let people think I'm something other than what I am. White lighters will not respect your beliefs or your right to self-interest. They generally do not possess the ability nor the will to understand, and after great efforts of explanation and reasoning, they revert to (or rather the general case, persist in) submission to the herd.

This is what I almost always do now, and it took me a long time to learn that it's the best way to spend the least amount of energy to deflect quite a large amount of trouble. In essence, it gives them nearly no information and allows the magic of mystery to take hold.