On the other hand, I’m pretty sure for like Mormons and JWs where they’re sending over like kids barely out of highschool for missionary work in another country that’s the entire point. They’re not there to convert anyone, they’re there to instil a sense of fear into these kids by showing them that everyone who isn’t apart of their church hates them even though they’re only trying to ‘help’. Being rude to them just proves their church’s point.
Or: actually the fastest way to get put on their blacklist is to be really genuinely nice (but still firm) to the missionaries because you’re proving them wrong about how mean and horrible the outside world is