The practice of disfellowshipping / expulsion IS BASED ON THE PRINCIPLES FOUND IN THE SCRIPTURES. In order to maintain God's favor and to be used by Him and to represent Him, the congregation must remain clean. Otherwise, God would expel or cut off the entire congregation. (Rev. 2:5; 1Cor. 5:5, 6.)
Examples and precedents have been set by the apostle Paul when he ordered the expulsion of an incestuous fornicator who had taken his father's wife. (1 Cor. 5:5, 11, 13) He also exercised disfellowshipping authority against Hymenaeus and Alexander. (1 Tim. 1:19, 20)
The Christian congregation is 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 about this loving practice: "Stop associating with him, that he may be ashamed. And YET DO NOT BE CONSIDERING HIM AN ENEMY, but continue admonishing him as a brother." (2 Thess. 3:6, 11, 13-15).
The Bible mentions some of the offenses that could merit disfellowshipping from the Christian congregation: fornication, adultery, homosexuality, greed, extortion, thievery, lying, drunkenness, reviling, spiritism, murder, idolatry, apostasy, and the causing of divisions in the congregation. (1Cor. 5:9-13; 6:9,10; Tit. 3:10,11; Rev. 21:8)
For more, see
Disfellowshipping / Expelling
Can someone be reinstated back to the congregation after being Disfellowshipped / Expelled?