Summary: Save the Church and Soul by Shunning
1 Cor 5:9-13
9 I wrote unto you in an epistle not to company with fornicators:
10 Yet not altogether with the fornicators of this world, or with the covetous, or extortioners, or with idolaters; for then must ye needs go out of the world.
11 But now I have written unto you not to keep company, if any man that is called a brother be a fornicator, or covetous, or an idolater, or a railer, or a drunkard, or an extortioner; with such an one no not to eat.
12 For what have I to do to judge them also that are without? do not ye judge them that are within?
13 But them that are without God judgeth. Therefore put away from among yourselves that wicked person. KJV
A sinner is a sinner and you expect one to act like one and the only way you can witness to them is to interact with them so eating with them is not a real problem. When I was in college I worked as a dockworker for a trucking company and lunch with the elect was not very profitable so I started sitting with guys I knew were not Christians so that maybe I could witness to them and win one. Never won any, but the guy who said grace for everyone out loud did not help. He only annoyed and angered the men making my task harder. We cannot escape interacting with unbelievers unless we can leave the earth. So make the most of the interaction for Christ.
However, when it comes to men that claim to be a Christian it is a different story. The Amish and the Mennonites call it shunning. Since they are openly living in sin and bringing a reproach to themselves and the Church as well as giving the enemies of Christ reason to blaspheme we are not to fellowship with them. Breaking bread as a part of fellowship was a part of the 1st Century Church and even today when Baptists meet they eat.
We should not associate with them as to do so would indicate to the unbelieving that we condone or even sanction their activities and we and the church will be labeled hypocrites or actors. We all have some sins that easily beset us and often they are not something that is open to the public. We need to deal with those as well and be humble when dealing with those in open sin recognizing that we are not perfect. Yet, we need to be firm in reproving them and if necessary strongly rebuke them.
A heretic is to be avoided after the first or second admonition. Since heresy involves doctrinal error and an unnecessary divisiveness we can apply the same concept to an unruly brother/sister who will not heed us. If he repents, then we are to forgive. If not, we are to shun. The hope is that he will become ashamed and miss the fellowship of the saints and Church bringing him to repentance. If not, worse than shunning may happen to him.