Albert Barnes Commentary Matthew 18:17

"And if he refuse to hear them, tell it unto the church: and if he refuse to hear the church also, let him be unto thee as the Gentile and the publican." — Matthew 18:17 (ASV)

Tell it unto the Church.

The church may here mean the whole assembly of believers, or it may mean those who are authorized to try such cases—the representatives of the church, or those who act for them. In the Jewish synagogue there was a bench of elders, before whom trials of this kind were brought. It was to be brought to the church in order that he might be admonished, entreated, and, if possible, reformed. This was, and is always to be, the first business in disciplining an offending brother.

If he neglect to hear the Church, let him be, etc. The Jews gave the name heathen or Gentile to all other nations but themselves. With them they had no religious fellowship or communion.

Publican.

Publicans were men of abandoned character, and the Jews would have no dealings with them. The meaning of this is to cease to have religious fellowship with him and to cease to acknowledge him as a brother. Regard him as obstinate, self-willed, and guilty.

It does not mean that we should cease to show kindness to him and aid him in affliction or trial, for this is required towards all people. Rather, it means that we should disown him as a Christian brother and treat him as we do other people not connected with the church. This should not be done until all these steps are taken. This is the only way of kindness. This is the only way to preserve peace and purity in the church.