SHAFAQNA – The Grand Ayatollah Vahid Khorasani answered a question about having association with the father of the wife who has corrupt belief.
Question: The father of my wife does not believe in religion, he is a usurer and makes fun of religious leaders. Is it correct to have association with him?
The Grand Ayatollah Vahid: If he believes in the unity of God and the Day of Judgment as well as the prophethood of the Prophet (PBUH) and the Imamate of Ahlul bait (AS) but his belief in religious issues are weak, and commits sins of usury and similar ones, association with him is allowed. But if he denies the basis and necessities of the religion and for example considers usury Halal or is an enemy of Imams (AS), if your association with him will not lead to his guidance, do not associate with him. If you think there is a possibility he will be guided you can associate with him and guide him, unless you fear this connection may corrupt your family.
Source: PERSIAN SHAFAQNA