I'm not a native speaker; I thought proselytising = evangelising work.

Did I get that exactly the wrong way around?

"Aside from" means "except for"... He said that most of them don't attempt to convert people's religion (proselytism) with Jehovah's witnesses being the exception.

Parse error on my side apparently: I read the "- aside from X, they do Y,... -" that "they" referred to X.