The Second Issue:

Istiḥlāl (deeming something permissible) is a matter of the heart; its essence is to believe in the permissibility of a certain action. Ibn Taymiyyah, may Allāh have mercy on him, said: «والاستحلال: اعتقاد أنها حلال له» "Istiḥlāl is believing that something is permissible for him" [Aṣ-Ṣārim Al-Maslūl (3/971)]. Ibn Al-Qayyim, may Allāh have mercy on him, explained: «فإن المستحل للشيء هو: الذي يفعله معتقداً حِلَّه» "The Mustaḥill (one who does Istiḥlāl of a something) is one who engages in it while believing it to be permissible." [Ighāthat Al-Lahfān (1/382)]. Ibn ’Uthaymīn, may Allāh have mercy on him, said: «الاستحلال هو: أن يعتقد الإنسانُ حِلَّ ما حرمه الله ... وأما الاستحلال الفعلي فيُنظر: لو أن الإنسان تعامل بالربا لا يعتقد أنه حلال، لكنه يُصِرُّ عليه؛ فإنه لا يكفر؛ لأنه لا يستحله» "Istiḥlāl is when a person believes in the permissibility of something that Allah has forbidden... As for practical Istiḥlāl, one must consider: if (for example) a person who engages in usury without believing it to be permissible but persists in it, they do not fall into disbelief because they do not consider it permissible." [Al-Bāb Al-Maftūḥ (3/97), Meeting 50, Question 1198]. I say: Since it is a matter of the heart, it can only be known by an explicit declaration of what one believes (see also the third and fourth issues on pages # and #).