In 1 Corinthians 5:13 Paul orders the ecclesia in Corinth to expel from their membership anyone who is immoral. His instructions arise from an incident where a brother in the ecclesia is sleeping with his stepmother and the ecclesia seems to think this is acceptable. It is worth noting that disfellowship in the New Testament was always for immoral behaviour.  It was not applied to brothers and sisters who were weak in faith or who had difficulties or doubts. Nor was it applied to people who neglected good apostolic advice.  A number of passages can be quoted from the New Testament which might seem to deny this statement, but a careful examination demonstrates that those who were to be withdrawn from were encouraging immoral behaviour. For example:

I appeal to you, brethren, to take note of those who create dissensions and difficulties, in opposition to the doctrine which you have been taught; avoid them. For such persons do not serve our Lord Christ, but their own appetites, and by fair and flattering words they deceive the hearts of the simple-minded.... ... I would have you wise as to what is good and guileless as to what is evil;  then the God of peace will soon crush Satan under your feet.                                                                       (Romans 16:17-20)

Note the contrasts between “serve our Lord Jesus Christ” and “their own appetites”, between “good” and “evil”, between “God” and “Satan”.

As for a man who is factious, after admonishing him once or twice, have nothing more to do with him, knowing that such a person is perverted and sinful; he is self-condemned.                                             (Titus 3:10-11)

The contrast in Titus 3 is between those who apply themselves to good deeds (submissive to rulers and authorities, obedient, ready for any honest work, not speaking evil of others, not quarrelling but being gentle and courteous to all – Titus 3:1-2) and those who go in for “stupid controversies, genealogies, dissensions, and quarrels over the law”. Paul is not talking here about proper and sensible discussion but about those who engaged in quarrelling and sought to create divisions.

Jude had similar people in mind when he appealed to ecclesias “to contend for the faith which was once for all delivered to the saints” (verse 3). The faith was being opposed by “ungodly persons who pervert the grace of our God into licentiousness” (verse 4). They are described as people “who set up divisions, worldly people, devoid of the Spirit” (verse 19).  Jude’s advice was:

But you, beloved, build yourselves up on your most holy faith;  pray in the Holy Spirit;  keep yourselves in the love of God;  wait for the mercy of our Lord Jesus Christ unto eternal life.  And convince some, who doubt;  save some, by snatching them out of the fire;  on some have mercy with fear, hating even the garment spotted by the flesh.                (Jude 20-23)

The practice of excommunication was reserved in the New Testament for those who were openly and persistently immoral. Immoral behaviour ranged from sexual misbehaviour on the one hand to quarrelling on the other. Amongst ecclesias today sexual immorality is comparatively rare and this term could not according to New Testament understanding cover things like marrying a non-believer. Though marrying “out” is undesirable for many reasons, there is no evidence that the New Testament would have approved disfellowship for this. Quarrelling and harsh words are sadly not unknown, and though according to New Testament standards these would have been grounds for considering excommunication, disfellowship seems never to be applied for these offences today.