Matthew 18:15-17

“If another believer sins against you, go privately and point out the offense. If the other person listens and confesses it, you have won that person back. But if you are unsuccessful, take one or two others with you and go back again, so that everything you say may be confirmed by two or three witnesses. If the person still refuses to listen, take your case to the church. Then if he or she won’t accept the church’s decision, treat that person as a pagan or a corrupt tax collector.