Take heed to yourselves
if your brother sins,
rebuke him;
and if he repents,
forgive him.
It has been suggested that Matthew expanded on this Q passage creating a three-step process meant for handling offenses in the community. This might well be the case since the Matthaean community were made up of Jewish converts who have had experience in community handled disputes. This, together with a remark by Paul in 1 Corinthians (1 Cor. 6:2-8) point us to a feature of the early Church that allowed it to handle legal matters within the community of faith.
Matthew 18:15-20 can be divided thus
15 The case of a brother who sins, is rebuked and repents (cf. Luke 17:3)
16 In case the brother does not repent: to be brought before witnesses
17 In case number 2 fails, the brother is brought before the Church; if still unrepentant, he is treated like "a Gentile and a tax collector"
18-20 Binding and loosing
From the outline above, it is clear that Matthew has expanded a Q passage to cover cases when the offender refuses to listen to fraternal correction. Verses 18-20 provides the rationale for the result of the process: Christ presiding over the community.
The Greek of Matthew 18:15 reads: "If your brother sins against you." What we have here is a case that can go from mere legal dispute (e.g. how an inheritance should be dealt with among brothers) to a personal offense that can be described as "sin". The brother should be rebuked, but Matthew adds "in private, between the two of you." The goal is reconciliation in keeping with the spirit of a passage like Matthew 5:25 ("Make friends quickly with your accuser, while you are going with him to court... ") . In case the offending brother repents, then reconciliation occurs. The phrase used is "you have gained your brother." The word kerdeso as used here may as well have the connotation of a missionary conversion. In this case it is the metaphoric use of a business term, the antonym of "losing x". To "gain someone" here means recovering one that has been lost. While the word "lost" or "be lost" is not used here, the phrase "you have gained your brother" makes this passage and the whole process until verse 17 a continuation of the theme of finding a lost sheep in Matthew 18:12-14. Sheep stray, are lost and when found by the shepherd remain "found." But what about human beings?
In the case above, the brother who sins against another is "lost" to that one until he repents and is reconciled. In case he does not repent, that is, "if he refuses to listen", then a second step is implemented: one in conformity with Jewish practise: to call in witnesses.
The second step in the process of reconciliation is based on Deuteronomy 19:15, but here Matthew introduces something new: instead of "two or three witnesses" as prescribed by Deuteronomy, "one or two" is deemed sufficient by the evangelist, since the offended party himself will be added to the number of witnesses. The function of the witnesses here is not similar to the one found in Deuteronomy 19:15, since in this latter, a charge is formulated for presentation in court. Rather, the witnesses continue the work of reconciliation that failed in the first step. If after this, the offending party refuses to repent, he is brought before the Church, the ekklesia, itself.
There are only two places where the word "Church" is used: in Matthew 16:18 and in this place (Mt. 18:17). The Pauline remark we have quoted above (1 Cor. 6:2-8) gives us the idea that here the local Church, the larger community, is the last recourse for drawing the offending party to repentance and conversion. The refusal to repent at this stage means that the offending party does not wish to be reconciled, and therefore, he is treated like "a Gentile or a publican" that is someone outside the Church and an object of its saving work. In other words, the unrepentant party is excommunicated, that is, placed outside the communion of the Church. While it is true that it is not God's will that anyone should perish (cf. Matthew 18:14), repentance is still a requirement for salvation.
Matthew 18:18-20 is to be understood within the process of decision-making that is described beginning verse 16. The authority of binding and loosing first given to Peter in Matthew 16:19 is given to the Church. The power "to bind and loose" originally meaning the rabbinic authority to interpret laws and implement them is an authority given to Peter first and then to the whole Church to fulfill its mandate to extend Christ's work of revealing, reconciling and forgiving: "as the Father has sent me, so I send you." Thus the Catechism rightly states:
The power to "bind and loose" connotes the authority to absolve sins, to pronounce doctrinal judgements, and to make disciplinary decisions in the Church. Jesus entrusted this authority to the Church through the ministry of the apostles(Matthew 18:18) (CCC 553)
The work of reconciling a brother who has sinned is carried out, first on the individual level, and then with the help of one or two others, and when these fail, the matter is raised to the level of the community of faith. The offense is after all was made not just to anybody, but to a member of the Body of Christ. The decisions made at each level of the process is validated on the basis of verses 19-20
19 Again I say to you,
if two of you agree on earth about anything they ask,20 For where two or three are gathered in my name,
it will be done for them by my Father in heaven.
there am I in the midst of them."
The phrase "I am there in the midst (of them)" reminds us of the "I AM" pronouncements of Jesus in Matthew 14:27 and 28:20. It is the Lord presiding over the Church who gives validity to the decisions made by the community. In this light, the "agreement about anything they ask" and the "gathering in my name" in vv. 19-20 respectively imply an event where people come together "as Church." Thus, from the moment the offending party refuses to repent and remains unreconciled, it is the Church, presided over by the Lord who meets him in the witnesses that are called to assist in the process and in the solemn assembly before whom he is summoned.
The passage from Matthew is a guideline for dealing with a possible source of breach iin the communal relationship within the community of faith. We have seen cases where misunderstanding among members of a community can escalate into a full-blown division within a Church community. The guideline in Matthew 18:15-20 prevents such an event from happening through a process the goal of which is to reconcile, that is, to move one to repentance so that forgiveness can be given. The context of the passage, Matthew 18:6-35 is all about not allowing someone to be lost and forgiving. The Church, by her life, is the agent of reconciliation, and extends the work of Christ. Hence, it does all that is necessary to effect repentance and reconciliation for those within and outside of her . Where a member's repentance is not made manifest, then the Church changes strategy: it begins to act as the agent of reconciliation not for those who are its members, but for those who are outside her communion. The open refusal of a member to repent in the face of sin renders himself outside the communion of a reconciling community. It is for this reason that excommunication is in a sense not the act of the Church but the act of someone who has made himself an outsider to the Church. It is for that reason too that he becomes a special object of the work of salvation, "like a Gentile and a tax collector."
