I have written you in my letter not to associate with sexually immoral people-- not at all meaning the people of this world who are immoral, or the greedy and swindlers, or idolaters. In that case you would have to leave this world. But now I am writing you that you must not associate with anyone who calls himself a brother but is sexually immoral or greedy, an idolater or a slanderer, a drunkard or a swindler. With such a man do not even eat. What business is it of mine to judge those outside the church? Are you not to judge those inside? God will judge those outside. "Expel the wicked man from among you."

Clearly, Paul did instruct Christians to expel from the congregation's fellowship any person who was purposely practicing willful sin. The disassociation would quite naturally exclude them from being greeted by the identifying "holy kiss," as well as not being allowed to share in meetings and the meals for Christian worship and prayer. However, Paul's instruction did not prohibit normal conversation or witnessing to former members. Nor were they barred from attending worship in the temple or the synagogues. Jesus, the apostles and Paul, along with the rest of the Jews, worshipped God both publicly in the temple and synagogues, and privately with small groups in various homes. (Acts 5:42) It was from the private Christian fellowship for worship that sinners were excluded.

If your brother sins against you, go and show him his fault, just between the two of you. If he listens to you, you have won your brother over. But if he will not listen, take one or two others along, so that 'every matter may be established by the testimony of two or three witnesses.' If he refuses to listen to them, tell it to the church; and if he refuses to listen even to the church, treat him as you would a pagan or a tax collector.

The Jehovah's Witnesses are hardly unique in sometimes removing folks from membership in the congregation.

"Almost any religious body would, on occasion, drop a membership - by request, due to inactivity or as a matter of discipline due to some kind of moral failure," said Ron Stansell, professor of religion studies at George Fox University.

Catholics, for instance, can be excommunicated - denied sacraments considered their means of salvation.

But the Jehovah's Witnesses are among a minority of Christian groups in the United States known to cut off social - and, as a result, business and family - contact with the disfellow- shipped.

Such shunning is "a fairly common practice of radical reformation sects, groups that tend to be drawn in very much on themselves," said Carl Raschke, a Denver University religious studies professor.

Other practitioners include certain Old Order Mennonite and Amish communities, Hutterites and the Bruderhof.
[...]

Disfellowshipping is not the most radical practice out there, Colorado College professor David Weddle said. Some ultra-orthodox Jewish congregations, for example, go so far as to hold funerals for former members who decide to marry outside the religion.

And in some extremist Islamic groups around the world, apostasy (renunciation of faith) is considered punishable by death - witness the bounty placed on author Salman Rushdie after he was branded an apostate for "The Satanic Verses."