Church discipline is the corrective and formative ministry of the church, guided by the Word of God, to preserve the purity of the body, restore the wandering, and uphold the honor of Christ. Reformed traditions emphasize this as an exercise of the 'power of the keys' to guard the sacraments and nurture members in holiness, while Particular Baptists affirm it as a necessary aspect of congregational government under the headship of Christ.
Discipline is the 'sinews' of the church, essential for its order and health. According to 1689 LBCF Ch.26 §12, all who enjoy church privileges are subject to its government. Its primary goals include reclaiming the sinning brother, deterring others from similar offenses, and purging the 'leaven' of sin to protect the unity and testimony of the body, as noted in Westminster Confession of Faith Ch.30 §3. As the apostle Paul wrote, we must guard against the influence of unrepentant sin lest it corrupt the whole: 'Your glorying is not good. Know ye not that a little leaven leaveneth the whole lump? Purge out therefore the old leaven, that ye may be a new lump, even as ye are unleavened' (1 Corinthians 5:6-7).
Discipline is both formative (teaching and training in righteousness) and corrective (rebuke and censure). When personal offenses arise, the process is clear: 'Moreover if thy brother sin against thee, go, show him his fault between thee and him alone: if he hear thee, thou hast gained thy brother. But if he hear thee not, take with thee one or two more, that at the mouth of two witnesses or three every word may be established. 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 18:15-17). Throughout this, the spirit must be one of gentleness and restoration, keeping in mind our own frailty: 'Brethren, even if a man be overtaken in any trespass, ye who are spiritual, restore such a one in a spirit of gentleness; looking to thyself, lest thou also be tempted' (Galatians 6:1).