What is the ruling on killing someone who insults Allah and His Messenger, and what are the limits of dealing with him if killing him is not permissible, and is it permissible to listen to him to refute his sophistry?

Whoever curses Allah Almighty or His Messenger, peace and blessings be upon him, commits an act of disbelief and becomes an apostate. He must be asked to repent; if he repents, then well and good, otherwise he is to be executed. The implementation of this punishment is the responsibility of the ruler or his deputy, and individuals are not permitted to carry it out. Rather, the matter must be referred to the relevant authorities.

One who curses Allah is treated as an apostate: he is not greeted with peace, his slaughtered animal is not eaten, no funeral prayer is offered for him if he dies, and he is not buried in Muslim cemeteries. It is obligatory to advise him and explain the gravity of his action. If he has misconceptions and you are able to refute them, then sit with him; otherwise, avoid his company.