1 Corinthians 5:11

In like manner keep yourselves separate from all those of whom the apostle makes mention when he says, "with such persons, no, not to eat; ". Those also are to be dealt with in like manner of whom he says, "With such persons, no, not …

Obviously if we are not to eat ordinary food with such people, we are not to admit them to the Lord's table either.

Brethren, be not deceived. If any man follows him that separates from the truth, he shall not inherit the kingdom of God; and if any man does not stand aloof from the preacher of falsehood, he shall be condemned to hell. For it is obligatory neither to separate from the godly, nor to associate with the ungodly. If any one walks according to a strange opinion, he is not of Christ, nor a partaker of His passion; but is a fox, a destroyer of the vineyard of Christ. Have no fellowship with such a man, lest ye perish along with him, even should he be thy father, thy son, thy brother, or a member of thy family. For says [the Scripture], "Thine eye shall not spare him." You ought therefore to "hate those that hate God, and to waste away [with grief] on account of His enemies." I do not mean that you should beat them or persecute them, as do the Gentiles "that know not the Lord and God;" but that you should regard them as your enemies, and separate yourselves from them, while yet you admonish them, and exhort them to repentance, if it may be they will hear, if it may be they will submit themselves. For our God is a lover of mankind, and "will have all men to be saved, and to come to the knowledge of the truth."

For since he had said, "Ye have not rather mourned, that such an one should be taken away;" and, "Purge out the old leaven;" and it was likely that they would surmise it to be their duty to avoid all fornicators: for if he that has sinned imparts some of his own mischief to those who have not sinned, much more is it meet to keep one's self away from those without: (for if one ought not to spare a friend on account of such mischief arising from him, much less any others;) and under this impression, it was probable that they would separate themselves from the fornicators among the Greeks also, and the matter thus turning out impossible, they would have taken it more to heart: he used this mode of correction, saying, "I wrote unto you to have no company with fornicators, yet not altogether with the fornicators of this world:" using the word "altogether," as if it were an acknowledged thing. For that they might not think that he charged not this upon them as being rather imperfect, and should attempt to do it under the erroneous impression that they were perfect, he shews that this were even impossible to be done, though they wished it ever so much. For it would be necessary to seek another world. Wherefore he added, "For ye must needs then go out of the world." Seest thou that he is no hard master, and that in his legislation he constantly regards not only what may be done, but also what may be easily done. For how is it possible, says he, for a man having care of a house and children, and engaged in the affairs of the city, or who is an artisan or a soldier, (the greater part of mankind being Greeks,) to avoid the unclean who are to be found every where? For by "the fornicators of the world," he means those who are among the Greeks. […]

You see, it was not only one fornicator, but others as well, and not just one vice, but various ones. But in what way can a brother also be an idolater? Just as the Samaritans were once only half-pious, so it happened with the Corinthians …

Then when he says, But rather, he presents the true interpretation. First, he states his intention; secondly, he assigns a reason (v. 12); thirdly, he draws the intended conclusion (v. 13b). First, therefore, he says: But rather I shall explain what I have written to …

Who is named a brother - That is, a Christian; especially if a member of the same congregation. Rapacious - Guilty of oppression, extortion, or any open injustice. No, not to eat with him - Which is the lowest degree of familiarity.

But now have I written unto you,....

“But now.” In this Epistle. This shows that he had written a former letter. I have written to you. - Above. I have designed to give this injunction that you are to be entirely separated from one who is a professor of religion and who is guilty of these things. Not to keep company - To be wholly separated and withdrawn from such a person. Not to associate with him in any manner.

There is less danger in associating with open worldlings than with carnal professors. Here, as in Eph 5:3, 5, "covetousness" is joined with "fornication": the common fount of both being "the fierce and ever fiercer longing of the creature, which has turned from God, to fill itself with the inferior objects of sense" [TRENCH, Greek Synonyms of the New Testament].

But now I have written - I not only write this, but I add more: if any one who is called a brother, i.e. professes the Christian religion, be a fornicator, covetous, idolater, railer, drunkard, or extortioner, not even to eat with such - have no communion with such a one, in things either sacred or civil. You may transact your worldly concerns with a person that knows not God, and makes no profession of Christianity, whatever his moral character may be; but ye must not even thus far acknowledge a man professing Christianity, who is scandalous in his conduct. Let him have this extra mark of your abhorrence of all sin; and let the world see that the Church of God does not tolerate iniquity.