My parents being attracted by Ahmadiyyah Faith

Quran doesn't say to chop off.

Whoever is doing a single thing against Islam no matter he/her is very religious its no a muslim. I mean if you are doing something wrong that belongs to you and Allah.

When you harm anyone even to kuffar aur munafiq if they are not doing any harm to you then you will be punished on judgement day. That's what quran say.