Excommunication
Excommunication in biblical contexts refers to formal exclusion from religious community, practiced in both Jewish and Christian settings. Jewish excommunication existed in three graduated forms: (1.) niddui — temporary exclusion for thirty days with certain restrictions on social contact; (2.) cherem — formal banning, stricter and more permanent; and (3.) shammatha — the most severe curse-like exclusion. The Mishnah lists twenty-four offenses punishable by excommunication. Jesus anticipates a form of this in Matthew 18:17 (let him be to you as a Gentile and a tax collector) and the Johannine community was familiar with being put out of the synagogue (aposynagogos, John 9:22; 12:42; 16:2).
In the New Testament, Paul exercises a form of excommunication in 1 Corinthians 5, commanding the church to deliver the incestuous man to Satan for the destruction of the flesh, so that his spirit may be saved in the day of the Lord. The goal is both the purity of the community and the restoration of the offender. 2 Thessalonians 3:14 instructs the church to have nothing to do with the disobedient, and 2 John 10 addresses refusing hospitality to false teachers. The purpose throughout is always the health of the body and the hope of the offender's repentance.