Ruling on declaring people disbelievers and discovering they are not

Q 5: What is the ruling on someone who, for some reasons, declares some people to be disbelievers? He later came to know that those people did not intend to commit disbelief. Even worse, he cursed their faith claiming that they were not Muslims. Among the reasons for which he declared them disbelievers is misinterpretation e.g., a person may spontaneously utter some words that imply glorifying someone other than Allah like saying to another, "you rank above any other one." The one who heard these words deemed the speaker to be glorifying a person more than Allah, therefore he declared the speaker to be a disbeliever and cursed his faith.

A: The legal proofs indicate that a Muslim must be sure of things and take time before passing judgments. This person was wrong when he declared some people to be disbelievers and cursed their faith. He must perform Tawbah (repentance to Allah), ask Allah's forgiveness, and ask the one whom he wronged to pardon him.May Allah grant us success. May peace and blessings of Allah be upon our Prophet Muhammad, his family and Companions!