The thing that guys like that (the anti-kilt guy) don't realize is that not everyone can be reached by "fire and brimstone".
I doubt his intention is to 'reach' anybody. He's just a nutjob who thinks he knows God's Will, and gets off on telling everyone else that they're going to hell. It's likely a chemical/mental disorder that causes people like this to do what they do for the enjoyment of making others miserable.

Please, folks, don't take him seriously. That's what he wants more than anything in the world.