Moreover if your brother shall trespass against you, go and tell him his fault between you and him alone: if he shall hear you, you have gained your brother. But if he will not hear you, then take with you one or two more, that in the mouth of two or three witnesses every word may be established. And if he shall neglect to hear them, tell it unto the church: but if he neglect to hear the church, let him be unto you as a heathen man and a tax collector. (Mat 18:15-17)

In the context of not allowing his little ones to be led into sin, Jesus now gives us instructions for church discipline. First, he says, we should go privately:

If for no other reason that this: if we're wrong, we won't be nearly so embarrassed.

By the same token, if he's wrong, we will not have stirred up his pride, and made things worse.

Consider too: if you have been wounded by him, and he doesn't know it, should you not prevent the next shot?

Why don't we do this?

Because we are afraid that our brother will be mad at us. But recall that perfect love casts out fear.

It may also be that our own sins are sufficient to haunt us. We do not go as judges, but as physicians—and the greater our sins, the more sincere our warning.

Is there any real harm in just letting it alone?
 

If we do, do we not condone the sin implicitly?

And do we not allow a bad situation to become worse?

Is it not possible that we are not the only victims—just the only known victims? Would you not have mercy on those unknown brothers?

If we fail to do this, does this not show a lack of love for our Christian brother—and thus for our Lord?

Warning: we are not to

Start by telling others. It says "just between the two.."

Criticize. We are here to heal, not destroy.

Go in self-love ("I'm so hurt") but in love of our brother.

You are to show your brother his fault . Not his sinfulness; his fault. The sin is to be exposed, the sinner to be loved. Does this sound fishy? How would you like it done if you were on the receiving end? Then go and do likewise.

Even if we need to escalate to other brothers, or even the whole church, the object is the same: the repentance (and forgiveness) of our Christian brother. Jesus did not say this was easy. He did say it is required. Better sooner than later, better one than a crowd, better a sinner restored than an outcast.