SHAFAQNA – The Grand Ayatollah Makarem Shirazi answered questions about the personal duty towards someone who wants to commit apostasy.
Question: One of my friends is serious about changing his religion from Islam to Christianity; by doing so, does he become an apostate? Is shedding his blood permissible? What is my religious duty towards him?
The Grand Ayatollah Makarem: If he does not express or announces his belief, he will not be punished. But he will go out of the religion, and his wife must also separate from him. And your duty towards him is that gently with politeness and respect prohibit him from the bad deed, and if that is not effective, cut your relation with him.
Source: PERSIAN SHAFAQNA