Mat 18:17 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 an heathen man and a publican.

This is a perfect example of how the success of Christianity itself has changed the meaning of Christ's words. The word he used for "church" didn't have that meaning at all. It was simply a assembly of local, regular people. The idea here is very close to our idea of a jury, a group of peers rather than a government agency.

If the person involved doesn't want to agree to the judgment of the group, it sounds like Christ is telling the community to shun him, but the sense of the original Greek is very different. The idea is that if someone won't agree to the personal judgment of those who know him, you have to treat him or her impersonally. This is how you treat someone you don't know or a government official. The matter then becomes a matter of law and not relationships. The distinction is a very big deal to Christ, who bases most of his teaching on the need for more personal relationships both with God and our fellow people.

Aternative: And if he won't listen to them, talk to the community: but if he won't listen to the community, his relationship to you like that of a stranger or a government official.

"Neglect to hear" is from parakouô, which means "to hear beside," "to overhear," "to hear imperfectly," "to overhear," "to misunderstand," "to hear carelessly," and "to pretend not to hear."

"Church" is from ekklêsia, which means an "assembly duly called." It come from two Greek words, "to call away from." It was used to describe an assembly of Jews. Through its use in the NT, it came to mean "church." However, it is only used twice in the Gospels, once here and in Mat 16:18 , when Christ tells Peter he is the rock on which this assembly will be built. The word only came into extensive use in the Act of the Apostles, which describes the formation of the Christian church or assembly. Christ could not have used to term in that sense, though Matthew (the word is not used in Mark, Luke, or John) could have translated Christ words based upon the usage this term acquired in the development of the early Church.

"Heathen man" is from ethnikos, which means "national," "provincial," "foriegn," and "gentile." It was used in the same way we would describe someone as an "ethnic" or "foriegner." Foreignors, the Greeks and Romans, were the rulers of the nation in Christ's time.

"Publican" is from telônês, which means "tax collector" and refers to any number of types of tax collectors. The idea was the these people worked as government agents. They were, of course, villified because they worked for foriegn occupiers.