Church discipline is a process commanded by Jesus for maintaining purity in the church and the reformation of the disciplined. This process necessitates regenerate church membership which was the exclusive practice of the New Testament church.
The authority to practice church discipline within the local church comes from the headship of Jesus. After Peter declared that Jesus is “the Christ, the Son of the living God” (Matt 16:16), Jesus declared that He would build His church upon Peter, and by extension, the other apostles (Eph 2:20). The apostles served as the foundation for the church by spreading their eye-witness account of Jesus’ person and work as the Messiah. Jesus tells the apostles that He will give them the keys to the kingdom of heaven and that they will practice binding and loosing in response to the binding and loosing which has happened in heaven (the perfect passive tense in used to indicate that the church is merely discerning what God has already decreed from His throne). This metaphor refers to sharing the gospel that people may be bound with Christ and the church while practicing discipline upon those who give evidence that they have not been genuinely bound to Jesus. The church submits herself to the headship of Jesus as she continues to be built upon the foundation of the apostles in the act of binding and loosing.
Matthew connects chapter eighteen closely with chapter sixteen in two ways. First, Matthew eighteen contains the only other use of the term church in the Gospels. Second, Jesus used the metaphor of binding and loosing in the context of discipline. This shows the headship of Jesus who builds His church on the foundation of the apostles.
In Matthew eighteen, Jesus revealed a three-step process of dealing with unrepentant sin in the church. First, one must go to the offender privately and show him his fault. If the offender repents, the process of discipline ends there. However, if he does not repent, the one who noticed the sin must include one or two other members of the church and confront the brother again. If the brother repents, discipline ends there. However, if he still does not listen, the witnesses must present the matter before the church so that the church may warn the offender. If the offender does not listen to the church, the church must excommunicate him, treating him as an unbeliever.
Paul also commanded the Corinthian church to practice discipline upon a man who is having sex with his step-mother. (1 Cor 5:1-13). In First Corinthians 5:2, Paul revealed that mourning over sin should be the attitude of the church who disciplines. Elsewhere, Paul included the need for a “spirit of gentleness” (Gal 6:1). In First Corinthians 5:4, Paul taught that the final stage of discipline must happen in the assembly of the church. In First Corinthians 5:5, he revealed the nature of discipline as an act of “deliver[ing] such a one to Satan for the destruction of his flesh.” Church discipline removes the offender from the spiritual protection of the church fellowship.
Paul provided two reasons for church discipline in First Corinthians 5:5-8. First, the church practices discipline “so that [the offender’s] spirit may be saved in the day of the Lord Jesus.” Church discipline is Jesus’ means for communicating the need for salvation to someone who shows evidence of being unregenerate. It is, in fact, a ministry of reconciliation in which the goal is to restore the brother to fellowship with God and the church. Second, Paul used the metaphor of leaven spreading through a lump of dough to reveal that the church must strive for holiness in Christ. Paul ended his discussion by reminding the people “not to associate with immoral people” (1 Cor 5:9) and to “[r]emove the wicked man from among yourselves” (1 Cor 5:13). After the Corinthian offender repented, Paul encouraged the church to forgive, comfort, and reaffirm their love for him (2 Cor 2:6-8). This again displays the goal of reconciliation.
In First Timothy 5:19-20, Paul spoke of practicing discipline upon an elder of the church with a public rebuke for continuing in sin. In Titus 3:10-11, Paul admonished to reject a factious man after two warnings. With these, and the above passages, the following guidelines should be exercised in church discipline. First, the church must practice discipline as an act of obedience to Jesus. Second, the church must practice discipline with a three-step process of rebuke: privately, with witnesses, and before the church assembly. Third, the church must practice discipline with an attitude of grief over sin and gentleness toward the offender. Fourth, in the practice of discipline, the church must seek the repentance and restoration to fellowship of the offender. Fifth, the church must use discipline to seek purity and protection of her reputation and therefore should practice discipline in an exclusive assembly of members. Sixth, the church must discipline for sins that are intentionally rebellious, public, and divisive in nature. Seventh, the church must end discipline when the offender repents of his sin.
 See Acts 2:37-42 where those who heard the gospel were commanded to repent and be baptized in Jesus’ name and three-thousand were added to their membership upon repentance and a trust in Christ displayed in their baptisms.
 See Colossians 1:15-20 and Ephesians 5:22-23 for statements of Jesus’ headship over the church.
 All Bible quotations are from the New American Standard Bible, 1995.
 In Ephesians 2:19-22, Paul teaches the Ephesians that those who follow Jesus are God’s household built upon the foundation of the apostles and prophets with Jesus as the corner stone. Also see Matthew 28:16-20 where the apostles are commanded to make disciples of all nations.
 Greg Allison defines church discipline as “a proleptic (or anticipatory) and declarative sign of the divine eschatological judgment, meted out by Jesus Christ through the church against its sinful members and sinful situations.” This recognizes the idea that the church is acting upon what God has already declared and what He will do in His Sovereignty and omniscience. See Gregg R. Allison, Sojourners and Strangers: The Doctrine of the Church (Wheaton: Crossway, 2012), 181.
 Jesus references Deuteronomy 17:6 where an accusation must be substantiated by two or three witnesses and disallowing a conviction to be made on the testimony of one person.
 See Galatians 6:1.