Growing up in a mainline Protestant church, I had no idea there was anything such as church discipline in the modern world. Matthew 18:15-17 was never discussed, much less implemented, even when church leaders gratuitously divorced their spouses after beginning affairs with other individuals.
In the evangelical churches I have participated in during my adult life, there has always been a policy regarding church discipline, attempting to be true to the teaching of Jesus in this text. But a number of exegetical observations are often overlooked:
First, nothing in this passage limits the sin to certain kinds of offenses deemed particularly serious. Matthew 5:23-24 could suggest that any individual’s priority is to deal with ways in which others in the congregation believe he or she has sinned against them. But for most small offenses, people should be able to deal with things privately, precisely the first step in the process. A willingness to freely apologize, even when one feels perhaps only partially responsible for an offense, can go a long way toward peacemaking, a task Jesus calls blessed (5:9)
Third, the different meanings of “witnesses” in English cause unnecessary confusion. I have often had people ask me, “How can I bring one or two witnesses if no one witnessed the offense?” This question confuses the concept of “eyewitness” (Greek autoptēs) with “one who testifies” (martus, the word used here). The point is not that the people must have prior knowledge of the offense, much less have actually seen it, but that they can testify after the meeting between the offender and offended as to what was said, how people reacted, and so on, so that it doesn’t come down to a case of “he said, she said.”
Fourth, there really isn’t any way to make “tell it to the church” mean “tell it to the pastor” or “tell it to the elders” or some other subgroup of the church. Perhaps involving a body of church leaders as an intermediate step between the meeting with one or two witnesses and telling things to the church is a wise idea, especially in all but the smallest of churches. If there is any chance that reconciliation can occur—repentance, followed by forgiveness and restoration of relationship—then the fewer people who know the better. There is wisdom in the principle of involving no more than those people who already know about a problem. But the “church” is the entire gathered assembly. Telling something to the church is the last step before disfellowshipping, and if there is the possibility that such a dramatic step must be taken then the entire body of believers must be informed and must be informed at least of the basic issue at stake. In today’s hyperlitigious society with confidentiality laws run amuck, churches who actually intend to implement church discipline need to have language in their by-laws and in agreements that members sign, approved by legal counsel, waiving the right to sue the church in such instances.
Finally, treating someone like “a pagan or a tax collector” means treating them like a non-Christian. Jesus was actually remarkably solicitous toward the immoral outsiders of his day, but he did call them to repentance. The only purpose for church discipline anywhere in the New Testament is always remedial, even if in extreme cases, the rehabilitation comes only after death! In this context, however, Jesus is not contemplating anything that extreme, not even full-fledged excommunication or disfellowshipping, but merely the exclusion of people from offices or gatherings that are limited to believers. If and when they repent, and demonstrate the genuineness of that repentance (which by definition is a change of action, requiring a period of time to show that the behavior truly has changed), then they may be reinstated, both to church membership and to leadership. In our fractured modern societies, in which full excommunication typically leads to a person merely going to another church that asks no questions or becoming embittered against the church, and possibly God, altogether, a much more effective approach is to declare the congregation’s love for an offender right from the beginning and offer a process of restoration and accountability that even before reinstatement does not require them to stop attending services (assuming those services are open to non-Christians) but certainly to refrain from the Lord’s Table and any gatherings open only to believers.