The scripture most often referred to as support for disfellowshipping is 1 Corinthians 5:9-13.

However, the Watchtower society views the situation in Corinth as being much worse than what needed to be dealt with in Thessalonica.

“Now we are giving you orders, brothers, in the name of the Lord Jesus Christ, to withdraw from every brother walking disorderly and not according to the tradition you received from us…

For your part, brothers, do not give up in doing right. But if anyone is not obedient to our word through this letter, keep this one marked, 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.”—2 Thessalonians 3:6, 13-15.

The following is taken from a 1999 Question From Readers article:

“On quite a different scale of gravity, Paul wrote to the Corinthians about one who practices gross sin and is not repentant. Such unrepentant sinners had to be excluded from the congregation. The “wicked” man had to be handed over to Satan, as it were. Thereafter, loyal Christians were not to mix with such wicked ones; the apostle John urged Christians not even to greet them. (1 Corinthians 5:1-13; 2 John 9-11) This, however, does not fit the counsel of 2 Thessalonians 3:14 either…

…Paul wrote that these were still ‘brothers,’ to be admonished and treated as such. Thus, the problem with the “disorderly” brothers was neither on the level of a mere personal matter between Christians nor of sufficient seriousness that congregation elders had to step in with a disfellowshipping action, as Paul did in connection with the immoral situation in Corinth. The “disorderly” ones were not guilty of grave sin, as was the man disfellowshipped in Corinth.

The “disorderly” ones in Thessalonica were guilty of significant deviations from Christianity. They would not work, whether because they thought Christ’s return was imminent or because they were lazy. Further, they were causing significant disturbance by ‘meddling with what did not concern them.’ Likely the congregation elders had repeatedly counseled them, in line with Paul’s advice in his first letter and with other divine advice. (Proverbs 6:6-11; 10:4, 5; 12:11, 24; 24:30-34) Still they persisted in a course that reflected badly on the congregation and that could spread to other Christians. So the Christian elder Paul, without naming the individuals, publicly called attention to their disorderliness, exposing their erroneous course.

He also let the congregation know that it would be appropriate for them as individual Christians to ‘mark’ the disorderly. This implied that individuals should take note of those whose actions corresponded to the course about which the congregation was publicly alerted. Paul advised that they “withdraw from every brother walking disorderly.” That certainly could not mean completely shunning such a person, for they were to “continue admonishing him as a brother.” They would continue to have Christian contact at the meetings and perhaps in the ministry. They could hope that their brother would respond to admonition and abandon his disturbing ways.

In what sense would they “withdraw” from him? Evidently, this was in a social context. (Compare Galatians 2:12.) Their ceasing to have social dealings and recreation with him might show him that principled people disliked his ways. Even if he did not get ashamed and change, at least others would be less likely to learn his ways and become like him. At the same time, these individual Christians should concentrate on the positive. Paul advised them: “For your part, brothers, do not give up in doing right.”—2 Thessalonians 3:13.

Clearly, this apostolic counsel is no basis for looking down on or judging our brothers who make some minor slip or error. Instead, its objective is to help one who takes a disturbing course that significantly conflicts with Christianity.

Paul did not lay down detailed rules as if trying to create a complicated procedure. But it is plain that the elders should first counsel and try to help a disorderly one. If they do not succeed and the person persists in a way that is disturbing and that has the potential for spreading, they may conclude that the congregation should be put on the alert. They can arrange for a talk on why such disorderliness is to be avoided. They will not mention names, but their warning talk will help to protect the congregation because responsive ones will take extra care to limit social activities with any who clearly display such disorderliness.

Hopefully, in time the disorderly one will be ashamed of his ways and will be moved to change. As the elders and others in the congregation see the change, they can individually decide to end the limitation they have put on personally socializing with him.

In summary, then: The congregation elders take the lead in offering help and counsel if someone is walking disorderly. If he does not see the error of his way but continues to be an unwholesome influence, the elders may warn the congregation by means of a talk that makes clear the Biblical view—be it of dating unbelievers, or whatever the improper course is. (1 Corinthians 7:39; 2 Corinthians 6:14) Christians in the congregation who are thus alerted can individually decide to limit any socializing with ones who clearly are pursuing a disorderly course but who are still brothers. (The Watchtower July 15, 1999 pgs. 29,30)

The article mentions: “Thus, the problem with the “disorderly” brothers was neither on the level of a mere personal matter between Christians nor of sufficient seriousness that congregation elders had to step in with a disfellowshipping action, as Paul did in connection with the immoral situation in Corinth.” However, it must be asked: “Where does Paul direct congregation elders to step in with a disfellowshipping action in 1 Corinthians chapter 5? Paul’s letter was addressed to the entire congregation. In his second letter Paul indicated that this action was taken by the majority of those in the congregation. (2 Cor. 2:6)

Additionally, if this was a lesser sin than that of the man in Corinth why were those in Thessalonica told to stop associating with the person? It is true that those in Thessalonica were told to “not be considering him as an enemy but continue admonishing him as a brother”. Hence it is assumed that when Paul tells the Corinthians to remove the wicked man from among yourselves, that this must be a more drastic step meaning that, because of the gravity of the situation, the entire congregation should cease all fellowship with the person. But if that were the case we would have to conclude that the Corinthians were to cease admonishing him, no longer consider him a brother but consider him an enemy.

The article also states that the elders take the lead in offering help and counsel if someone is walking disorderly and may warn the congregation by means of a talk. But Paul’s letter was addressed and read to the entire congregation not privately among the elders. Moreover, he gives no instructions for the elders to give a warning talk.

Furthermore, nowhere in 1 Corinthians does Paul say that no one should give a greeting to the man. The admonition in 2 John 9-11was given at an entirely different time and was an entirely different type of sin. John was giving instructions on how to deal with a person who was deceptively teaching things against Christ.

To be continued in Part 2