Q: Is it permissible to say out loud words of kufr and shirk when you are teaching someone to not say them? For example can you say “You should not say things like I am a Kaafir even jokingly” to someone to teach them? Or say “It is not right to say Merry Christmas”?
A: Yes. You are preventing him from wrong.
And Allah Ta’ala (الله تعالى) knows best.
Mufti Ebrahim Salejee (Isipingo Beach)