First, discipline aims to expose. Sin, like cancer, loves to hide. Discipline exposes the cancer so that it might be cut out quickly (1 Cor. 5:2).Second, discipline aims to warn. A church does not enact God’s retribution through discipline. Rather, it stages a small play that pictures the great judgment to come (v. 5). Third, it aims to save. Churches pursue discipline when they see a member taking the path toward death, and none of their pleading and arm-waving causes the person to turn around. It’s the device of last resort for bringing an individual to repentance (v. 5). Fourth, discipline aims to protect. Just as cancer spreads from one cell to another, so sin quickly spreads from one person to another (v. 6).Fifth, it aims to present a good witness for Jesus. Church discipline, strange to say, is actually good for non-Christians, because it helps to preserve the attractive distinctiveness of God’s people (v. 12).
-Jonathan Leeman, Church Discipline: How the Church Protects the Name of Jesus (9marks: Building Healthy Churches, pg. 33