What does Matthew 18:15 mean?

In the previous verses, Jesus has warned His disciples about the grave seriousness of leading any of the other believers into sinfulness. He has also warned them not to despise or disrespect other believers, even ones who have gone astray. After all, God the Father's will is that none of the believers in Jesus should perish or be eternally separated from Him (Matthew 18:10–14).

But what should the community of believers do if someone does fall into sin? How can they both take sinfulness seriously and attempt to bring the sinner back to faithfulness? Jesus gives a process for doing exactly that.

He begins by describing a scenario in which one among them sins. Some scholars question how the words "against you" should be read in this verse. Some earlier Greek manuscripts don't have those two words, simply saying "If your brother sins." Is Jesus talking about someone who sins only against another believer? Or someone who offends or does something disagreeable? Or is this someone who sins in any obviously and truly clear way? It's reasonable that the same process should be applied in all cases.

If another believer in Jesus sins against us—or if we become aware of the clear and obvious sin of another Jesus-follower—Jesus insists that the first step is always to have a private conversation with the person. This is often the most effective step in helping anyone to recognize and repent from sin. However, it's only likely to work if one approaches that person in childlike love and humility and without despising him or her. The goal is to keep this person as a brother or sister, not to shame or humiliate them.

If the result is not repentance, and we are still convinced of this person's ongoing sin, it is time to carefully bring someone else into the conversation (Matthew 18:16).