But if thy brother sin against thee, go, reprove him between thee and him alone. If he hear thee, thou hast gained thy brother.
Just before this verse, the Lord pictures a shepherd leaving ninety-nine sheep to find one that strayed. That picture shapes what follows. The question is not how to win an argument, but what love does with a private injury: who moves first, who else hears about it, and what counts as a good outcome.
The pattern behind the command
The Lord asks us to treat an offending brother the way God treated us. One writer draws that line from the gospel to your next step.
Suppose your brother does you wrong. Perhaps it is an evil word, or an unkind action done against you. You feel it as a real personal wrong against you. It is a sin, of course. Nobody knows it, probably, but himself and you. What are you to do? At once this great principle is applied: when you were ruined and far from God, what met your case? Did God wait till you put away your sin? He sent His own Son to seek you, to save you... The flesh feels and resents wrong done against itself. But grace does not shroud itself in its own dignity, waiting for the offender to come and humble himself and own his wrong.
Be certain of the wrong first
The words "sins against you" describe a fact, not a suspicion. One writer presses this before you take any step.
First of all, I must be sure that my brother has actually trespassed against me. "If your brother sins against you" — this is not if I think he has, or hearsay that he has. It is a definite case of one person wronging another. It is not a case where both parties have wronged each other, but of one alone sinning against the other.
Not silence, and not distance
Saying nothing can look like patience. Writers warn that it fails the very person it seems to spare.
The natural course might be to avoid him and say nothing about his fault. Or we might decide to bear the injury patiently towards the offender and, as people sometimes put it, "try to live it down." That might seem very plausible at first, and look like grace on my part. But it leaves out one all-important thing: the spiritual condition of my offending brother. Whoever may commend it, it is certainly not the Lord's way of treating the matter.
The single word "go" also settles the method.
The Lord says "go," and that is what we must do.
added: quote re-prints the featured verse (over half the quote) and misquotes ESV with "But" There is nothing here about writing to the brother or taking the matter up with him from a distance.
Why it must stay between two
"Between you and him alone" rules out our most natural instinct: finding someone to take our side.
Perhaps there is some brother whom we know is not on the best terms with the one who has injured us. We have little doubt he will listen readily to the tale of our wrongs. The danger is that in our selfishness we go to him. Yet if we cared about his soul's welfare, he would be the last person in the church we should whisper such a thing to... It is much to be feared that we are not altogether sorry to be able to punish our brother by lowering him in the eyes of others.
Privacy also serves the aim of the whole step.
This governs everything in this first step: "go and tell him his fault" — literally, "convict him," bring him to conviction — "between you and him alone." Let there be no needless exposure, no pain that can be spared, nothing that would arouse resentment and so surely hinder recovery.
What success looks like
Notice what the Lord does not promise the injured party.
The Lord does not say, "If he listens to you, all your wrongs will be put right." He says, "If he listens to you, you have gained your brother." No doubt, if grace works in him, if he is truly "gained," one of the first fruits will be a strong desire to put those injuries right. But securing that must not be the motive that sends me to him. Leaving my wrongs with the Lord, I am to seek my brother's blessing.
Aiming to gain him changes the one who goes, too.
If my errand to my brother were only to pain him, the task could easily be done without any exercise of heart. But if I am to gain him, then grace must work both in him and in me.
When the first step fails
Verse 15 is only the first move. Further steps follow if it fails.
Supposing trespasses arise, all the resources of grace were to be tried before treating an offender as a Gentile and a tax collector.
Summary
- Pattern. God did not wait for you to fix your sin before He sought you; the wronged one moves first because that is how grace acts.
- Certainty. Act on a real wrong: not a suspicion, not hearsay, not a quarrel where both sides have injured each other.
- Privately. Go yourself, face to face, alone — not by letter, not through sympathisers who will take your side.
- Plainly. Silence is not grace. Name the fault, and aim at conviction rather than exposure.
- To gain. The goal is your brother restored, not your grievance settled. Leave your wrongs with the Lord, and every later step becomes one more try at recovery.