"The judicial excommunication, or disfellowshipping, of delinquents from membership and association in a community or organization. With religious societies it is a principle and a right inherent in them and is analogous to the powers of capital punishment, banishment, and exclusion from membership that are exercised by political and municipal bodies."
In the congregation of God it is exercised to maintain the purity of the organization doctrinally and morally. The exercise of this power is necessary to the continued existence of the organization and particularly so the Christian congregation. The congregation must remain clean and maintain God’s favor in order to be used by him and to represent him. Otherwise, God would expel or cut off the entire congregation".—Re 2:5; 1Co 5:5, 6.
Jehovah God took expelling, or disfellowshipping, action in numerous instances. He sentenced Adam to death and drove him and his wife Eve out of the garden of Eden. (Ge 3:19, 23, 24) Cain was banished and became a wanderer and a fugitive in the earth. (Ge 4:11, 14, 16) The angels that sinned were thrown into Tartarus, a condition of dense darkness in which they are reserved for judgment. (2Pe 2:4) Twenty-three thousand fornicators were cut off from Israel in one day. (1Co 10:8) Achan was put to death at Jehovah’s command for stealing that which was devoted to Jehovah. (Jos 7:15, 20, 21, 25) Korah the Levite along with Dathan and Abiram of the tribe of Reuben were cut off for rebellion, and Miriam was stricken with leprosy and eventually might have died in that condition if Moses had not pleaded for her. As it was, she was expelled from the camp of Israel under quarantine seven days".—Nu 16:27, 32, 33, 35; 12:10, 13-15.
Based on the principles of the Hebrew Scriptures, the Christian Greek Scriptures by command and precedent authorize expulsion, or disfellowshipping, from the Christian congregation. By exercising this God-given authority, the congregation keeps itself clean and in good standing before God. The apostle Paul, with the authority vested in him, ordered the expulsion of an incestuous fornicator who had taken his father’s wife. (1Co 5:5, 11, 13) He also exercised disfellowshipping authority against Hymenaeus and Alexander. (1Ti 1:19, 20) Diotrephes, however, was apparently trying to exercise disfellowshipping action wrongly.—3Jo 9, 10.
Some of the offenses that could merit disfellowshipping from the Christian congregation are fornication, adultery, homosexuality, greed, extortion, thievery, lying, drunkenness, reviling, spiritism, murder, idolatry, apostasy, and the causing of divisions in the congregation. (1Co 5:9-13; 6:9, 10; Tit 3:10, 11; Re 21:8) Mercifully, one promoting a sect is warned a first and a second time before such disfellowshipping action is taken against him. In the Christian congregation, the principle enunciated in the Law applies, namely, that two or three witnesses must establish evidence against the accused one. (1Ti 5:19) Those who have been convicted of a practice of sin are reproved Scripturally before the “onlookers,” for example, those who testified concerning the sinful conduct, so that they too may all have a healthy fear of such sin.—1Ti 5:20.
The Christian congregation is also admonished by Scripture to stop socializing with those who are disorderly and not walking correctly but who are not deemed deserving of complete expulsion. Paul wrote the Thessalonian congregation concerning such: “Stop associating with him, that he may become ashamed. And yet do not be considering him as an enemy, but continue admonishing him as a brother.”—2Th 3:6, 11, 13-15.
However, regarding any who were Christians but later repudiated the Christian congregation or were expelled from it, the apostle Paul commanded: “Quit mixing in company with” such a one; and the apostle John wrote: “Never receive him into your homes or say a greeting to him.”—1Co 5:11; 2Jo 9, 10.
Those who have been expelled may be received back into the congregation if they manifest sincere repentance. (2Co 2:5-8) This also is a protection to the congregation, preventing it from being overreached by Satan in swinging from condoning wrongdoing to the other extreme, becoming harsh and unforgiving."—2Co 2:10, 11.