Just make them utterly hated and shut them out from society. Refuse to render any aid to them and openly discriminate against offering them any kind of services. Add in some police harassment and they will cut this shit out.
All the second generation needs is a good beating to get it out of their systems.
Hardliners are not mentally unstable just because you think people can't be sane and do these things. For all intents and purposes they are mentally healthy in the eyes of the law in most cases. I think you are just incapable of understanding or underestimating just how much religious dogma can influence a persons behavior.
If it's used the same way as "oh my god", they will.
This is a plausible response from an annoyed person trying to get away from some Jehovah's witnesses:
"Christ, please stop talking to me, I'm a goddamn atheist"
It's just part of the language, doesn't require any religious belief.
Mother pus bucket!