Does a person commit an act of disbelief (kufr) by going along with someone who jokingly says, "I will become a messenger"? Is it sufficient to disapprove with one's heart and facial expressions to avoid disbelief? What are the implications of such an act of disbelief? And what is the best way to object to such a statement in the future, along with the evidence?

Whoever sits with a person who speaks disbelief, while his heart is assured of faith, does not become a disbeliever by that. The similitude in His Almighty's saying, "Indeed, you would then be like them," means sharing in the sin, not disbelief. Ibn Kathir, Al-Nasafi, and Ibn Ashour have clarified that the verse implies sharing in the burden of sin or disobedience. A Muslim must denounce evil to the best of his ability, and the weakest form of faith is denouncing it in the heart, as stated in the hadith: "Whoever among you sees an evil, let him change it with his hand; if he cannot, then with his tongue; if he cannot, then with his heart, and that is the weakest of faith." The Sheikh of Islam affirmed that whoever sits and listens to evil and does not denounce it with his heart, tongue, or hand, is sinful. The questioner's hatred and denunciation of what occurred in his heart, and his dissatisfaction with it, indicates that he has not disbelieved. It would have been appropriate to promptly offer advice and clarification.