It's a shame that Matthew 18:15-20 is one of the most misused and misapplied passages of Scripture: its true purpose is saving souls!
All verse references are from Matthew 18 unless otherwise noted.
Verse 15 starts: “If your brother sins against you....” The sin in this passage is a personal sin one against another. In his follow-up question at verse 21, Peter understands the sin to be personal: “Lord, how often shall my brother sin against me and I forgive him?”
The Lord wants this matter to stay private. Why tell your brother his fault “between you and him alone?” Because, “If he listens to you, you have gained your brother” (verse 15). This teaching is consistent with Jesus' other teachings about doing our good deeds “in secret” (Matthew 6:1).
Even if you suffer great loss, the sinner's lost salvation is greater still.
Remember the desired outcome: “...you have gained your brother.”
This brother who has sinned against you is not an enemy, and even our enemies are to have our love and prayers in Jesus' teaching (Matthew 5:44).
If your brother has not listened to you, bring one or two others with you to be sure everything is understood (verse 16). Maybe you only think you've been wronged; maybe he just needs a firmer nudge.
Galatians 6:1 gives instructions with similar overtones for restoring in gentleness a brother who is overtaken by sin. In Galatians, only a few who are spiritual should go, and even those few must watch out for temptation: good advice for the “one or two others” of Matthew 18.
The Lord had wanted this matter private, but He commands the church to act if the sinner persists. The church must, “...let him be as a Gentile and a tax collector” (verse 17). This means to withdraw from him and let him be ashamed of himself (1 Corinthians 5:11; 2 Thessalonians 3:14).
Please take note, dear reader. The purpose of church discipline and the purpose of Matthew 18:15-20 are the same: the salvation of the sinner!
Regarding discipline, 2 Thessalonians 3:15 urges us, “Do not regard him as an enemy but warn him as a brother,” and 1 Corinthians 5:5 gives the rationale: “...so that his spirit may be saved in the day of the Lord.”
Again, the sinning brother risks eternity in hell. We must diligently do our Father's business, saving the lost.
The brother Corinth disciplined repented! The command to the church at Corinth then becomes, “...Turn to forgive and comfort him...,” and, “...Reaffirm your love for him...” (2 Corinthians 2:7-8).
Jesus follows up this instruction with three promises in verses 18-20 demonstrating God's, “...will [is] done on earth as it is in heaven” (Matthew 6:10).
Binding and loosing
The first promise is: “Whatever you bind on earth shall be bound in heaven, and whatever you loose on earth shall be loosed in heaven” (verse 18). When we follow Jesus' instructions, we are merely doing the will of heaven's God here on earth.
If you forgive your brother, God has also forgiven him; if the church disciplines our brother, God is getting his attention. Compare 2 Corinthians 2:10, “Anyone whom you forgive, I also forgive.”
If two of you agree
The second promise is: “If two of you agree on earth about anything they ask, it will be done for them by my Father in heaven” (verse 19). God will grant your requests when you and your brother are reconciled. The brother should pray for forgiveness and resolve; you pray for a good heart to forgive and comfort him.
Never remember where you buried the hatchet. Again, compare 2 Corinthians 2:11, “...so that we would not be outwitted by Satan; for we are not ignorant of his designs.”
I am there
The final promise from the Lord is that He goes with us when we go to restore our brother: “where two or three are gathered in My name, there am I among them” (verse 20). The “two or three” in this verse are the “one or two others” plus you in verse 16 above.
What courage it gives us that Jesus goes with us! As the true song says, “If Jesus goes with me I'll go anywhere!”
Jesus' work on earth was to seek and save the lost. We must be like Him.