What is your advice for those who engage in matters of declaring someone a disbeliever, labeling someone an innovator, and boycotting a person without knowledge, and who disparage those who differ with them?

Question:
What is your advice for those who engage in matters of declaring someone a disbeliever, labeling someone an innovator, and boycotting a person without knowledge, and who disparage those who differ with them?

Answer:
This is misguidance. It is misguidance for a person to enter into matters he does not know or is not skilled in, such as matters of creed and matters of religion. It is not permissible for a person to speak except with knowledge and understanding. Even in a place of need, he should restrain his tongue from harm, foul language, declaring someone a disbeliever, labeling someone an innovator, and declaring someone an open sinner. He should restrain his tongue from this so that he does not describe a believer with these descriptions, for the sin would return to him. If a person says to his brother, "O disbeliever, O enemy of Allah," and if the one addressed is indeed such, otherwise the sin returns to him and his foul words return to him. It is a serious danger.