What is the meaning of believing a sin to be good (hasana) or approving of it, which is considered disbelief (kufr)? Does this imply the removal of the Shar'i (Islamically lawful) detestation for sin? And does this apply to one who detests something permissible (mubah) with a Shar'i detestation?

Appreciating a sin constitutes disbelief (kufr) if it implies deeming it permissible (istihlal), being content with it, and believing that the ruling of its prohibition is invalid. The lowest level of faith is disliking sins in one's heart. Whoever is pleased with evil has disbelieved, just as whoever does not denounce evil in their heart, after being unable to strive against it with their hand and tongue, does not possess a mustard seed's weight of faith. The natural inclination to love a sin, coupled with the firm conviction of its prohibition, does not render its perpetrator a disbeliever; rather, he is considered a transgressor (fasiq). This differs from one who deems a sin permissible. A Muslim may naturally love a sin while legally detesting it. Weakness of faith can lead to the triumph of the natural inclination to love.