10 not at all [meaning] with the fornicators of this world, or with the covetous and extortioners, or with idolaters; for then must ye needs go out of the world: 11 but as it is, I wrote unto you not to keep company, if any man that is named a brother be a fornicator, or covetous, or an idolater, or a reviler, or a drunkard, or an extortioner; with such a one no, not to eat. 12 For what have I to do with judging them that are without? Do not ye judge them that are within?
Matthew Henry's Commentary on 1 Corinthians 5:10-12
Commentary on 1 Corinthians 5:9-13
(Read 1 Corinthians 5:9-13)
Christians are to avoid familiar converse with all who disgrace the Christian name. Such are only fit companions for their brethren in sin, and to such company they should be left, whenever it is possible to do so. Alas, that there are many called Christians, whose conversation is more dangerous than that of heathens!