What is the optimal approach for advising and dealing with an adolescent who curses the Divine Being and religion, and how should one act regarding that?

If the adolescent has not reached puberty, he should be advised kindly, and his family should be alerted to the seriousness of the matter. However, if he has reached puberty, then insulting Allah and religion is major disbelief (kufr akbar) that expels one from the fold of Islam. He must be reminded of the punishment for this, and if he persists, then he is an apostate who should be treated as such. Dislike for his action must be shown, and it is not permissible to sit with him while he is insulting religion, except with the intention of admonishing him and advising him to repent.