How should one deal with a son who tore the Qur’an and threw it in the toilet, and refuses to repent, while his father has forsaken him and his mother is trying to persuade him to repent despite his ill-treatment of them?

Whoever tears a copy of the Qur’an and throws it in the toilet, while being sane and acting of their own free will, has committed an act of disbelief (kufr) and exited the fold of Islam. If, in addition to that, they abuse their parents, they have combined disbelief with filial disobedience (uquq). They must be advised, and the gravity of their action and its dire consequences should be explained to them. They should be approached gently, and someone who can influence them should be brought to bear. If they repent, then praise be to Allah. But if they persist in their error, then boycotting them is legislated and may even become obligatory, while considering what is more beneficial: boycotting them or trying to win them over.