The Ruling on the Slaughter of a Person Whose Beliefs are Unknown and One Who Commits Shirk Due to Ignorance
Question :
May the meat be eaten of an animal slaughtered by one.
whose beliefs are unknown, and one who is negligent and easygoing regarding sins when he knows that they are forbidden and one about whom it is known that he supplicates to the jinn without an intention?
Answer:
If it is not known that he is guilty of Shirk, then his slaughter is permissible, as long as he is a Muslim and he testifies that none has the right to be worshipped except Allah and that Muhammad is the Messenger of Allah. And, if nothing is known of him that would necessitate (a verdict of) disbelief.
Then his slaughter is permissible, unless it is known that he has committed some kind of Shirk. For example supplicating to the jinn or supplicating to the dead and seeking help from them. Because these are forms of major Shirk and the sacrifice of such person may not be eaten. Examples of supplicating to the jinn include saying (to them): "Do this," or "Do that," or "Give me this," or "Give me that," or "Do such-and-such to so-and-so."
Likewise the one who supplicates to the inhabitants of the graves, or supplicates to the angels and seeks help from them. Or one who swears oaths to them all of these things are types of major Shirk and we ask Allah to save us and protect us from them.
As for sins, they do not prevent us from eating the sacrifice of one who commits any of them, as long as he does not declare to be permissible. In fact, it is permissible, as long as he slaughtered it in accordance with the Islamic Law.
But as for one who declares the sins permissible, he is considered a disbeliever. For example, one who declares adultery lawful, or drinking alcohol, or interest, or disobedience to one's parents, or untruthful testimony, or other sinful acts upon whose prohibi- tion there exists a consensus of opinion among the Muslims.
We ask Allah to protect us from all that incurs His Wrath.
Source:
Ibn Baz
Fatawa Islamiyah, Vol. 6 Pages 283-284