BENEFIT 376: What is the criterion for istihlal (deeming something permissible) that results in disbelief?

Sheikh Uthaymeen raḥimahullāh said: Istihlal refers to believing that something Allah has forbidden is lawful. When it comes to practical istihlal—acting upon this belief—its ruling depends on the nature of the action: -> If the action itself constitutes disbelief, then the person is deemed a disbeliever and has apostatised. -> For instance, if someone engages in riba (usury) while recognising that it is prohibited but continues to do so, he is not considered a disbeliever because he does not view it as lawful. However, if he explicitly declares riba to be permissible—referring to the very type that Allāh has forbidden—then he falls into disbelief, as this constitutes denial of Allāh and His Messenger. Thus, istihlal can take two forms: 1. Belief-based Istihlal: When a person inwardly believes that a prohibited act is lawful. 2. Action-based Istihlal: When a person’s actions are examined to determine whether they amount to disbelief. It is established that consuming riba does not render a person a disbeliever, though it remains a major sin. However, prostrating to an idol is an act of kufr because the action itself constitutes apostasy. A crucial condition must also be considered: the excuse of ignorance must not be applicable. If someone is unaware of a ruling—such as a new Muslim who does not yet know that alcohol is prohibited—then even if he mistakenly believes it to be lawful, he is not considered a disbeliever until he is informed of the correct ruling. If he persists in his belief after gaining knowledge, only then does he fall into disbelief. [Liqā’ Al-Bāb Al-Maftūḥ, Session 50]