“Moreover if your brother sins against you, go and tell him his fault between you and him alone. If he hears you, you have gained your brother. 16 But if he will not hear, take with you one or two more, that ‘by the mouth of two or three witnesses every word may be established.’ 17 And if he refuses to hear them, tell it to the church. But if he refuses even to hear the church, let him be to you like a heathen and a tax collector.
18 “Assuredly, I say to you, whatever you bind on earth will be bound in heaven, and whatever you loose on earth will be loosed in heaven.
19 “Again I say to you that if two of you agree on earth concerning anything that they ask, it will be done for them by My Father in heaven. 20 For where two or three are gathered together in My name, I am there in the midst of them.” — Matthew 18:15-20
Now Jesus explains how the members of his church (which he said he was going to build — see Matt. 16:18) should deal with someone who sins against another, or, more specifically, how to deal with someone who despises another brother.
The initial step is to confront the brother privately and show him his fault. The aim is to win him over, not to destroy him. The one who does this must do it with true humility and in love.
Then, if the private confrontation does not work, the next step is to take two or three witnesses and try to bring about a change (Deut. 19:15). The use of witnesses shows the link between the kingdom of the Messiah and the Israelite community of the Old Testament period. The united testimony of the witnesses would establish the resolution.
If the guilty person refuses to submit to the considered judgment of the people of the Messiah, the church, then that one is to be treated as a pagan. This does not mean here to treat the guilty with compassion (just because Jesus had compassion on the pagans and tax collectors). Jesus has in mind barring the guilty from the community until he repents. Each member of the church is to abide by the corporate judgment of the church with the responsibility of ensuring the good of the Christian community.
“bind. . .loose” – v.18. These words might alternatively be rendered “forbid” and “permit.” They were both rabbinical terms for legal decisions about how the Law should be applied to an existing situation.
Verses 19 and 20 are not a general promise for prayer, as if to say anything we pray for if a couple of people agree on it then God must do. Teachings on prayer occur in other places, but here they are concerned with the confrontation of an offending brother. The text does not say they pray, just if they agree “about anything” – here “any judicial matter.” The two who agree are probably the offender and the one against whom the offense has been committed. So if they come to a resolution and agree, it will be allowed, ratified–it will “come about.” This is because they prayed and came to a wise decision, and God’s binding and loosing stands behind the process followed (it was done according to God’s will) – God’s presence stands with his judges/elders.