“Go and tell his fault, between you and him alone.”
Jesus is not saying that we should be fault-finding of one another. Instead He is telling us to take our brother aside if he sins against us. We are to discuss his sin privately, not publicly.
If our brother listens, our relationship is restored. Here is God’s objective — restoration.
If he does not listen, only then do we bring together witnesses. Here, it becomes a charge. This step is serious, and is not to be taken lightly. We are making his sin public. And, this is not God’s objective. God prefers that sin remain private, between the two persons it has affected.
If your brother does not listen to your witnesses, only then do you take it “to the church.” Before moving to this step, you should spend time in prayer for your brother, asking the Holy Spirit to do His great work in the heart of your fellow Christian. Once public, sin can never be forgotten by the body of Christ. Of course, the sin and sinner can be forgiven but human beings have great difficulty forgetting a sin.
If your brother does not listen to the church, Jesus says “let him be to you as a Gentile and a tax collector.” Of course, this is definitely not God’s objective. God does not want your brother outside the church. Rather, God wants him restored. Therefore, always go to your fellow Christian in private, behind a closed door to confront and rebuke gently. Give plenty of time for repentance; do not rush to witnesses and a charge. Allow the Holy Spirit to work as He has great power. Pray, fast, wait. Your brother is likely to apologize and come back to you whole.