Since you would have required. It is as to this clause especially that interpreters are not agreed. For some say, "You must sooner quit Greece." Ambrose, on the other hand, says, "You must rather die." Erasmus turns it into the optative, as if Paul said, "Would that it were allowable for you to leave the world altogether; [1] but as you cannot do this, you must at least quit the society of those who falsely assume the name of Christians, and in the meantime exhibit in their lives the worst example." Chrysostom's exposition has more appearance of truth. According to him, the meaning is this: "When I command you to shun fornicators, I do not mean all such; otherwise you would require to go in quest of another world; for we must live among thorns so long as we sojourn on earth. This only do I require, that you do not keep company with fornicators, who wish to be regarded as brethren, lest you should seem by your sufferance to approve of their wickedness." Thus the term world here, must be taken to mean the present life, as in John 17:15 I pray not, Father, that thou shouldest take them out of the world, but that thou shouldest deliver them from the evil. Against this exposition a question might be proposed by way of objection: "As Paul said this at a time when Christians were as yet mingled with heathens, and dispersed among them, what ought to be done now, when all have given themselves to Christ in name? For even in the present day we must go out of the world, if we would avoid the society of the wicked; and there are none that are strangers, when all take upon themselves Christ's name, and are consecrated to him by baptism." Should any one feel inclined to follow Chrysostom, he will find no difficulty in replying, to this effect: that Paul here took for granted what was true -- that, where there is the power of excommunication, there is an easy remedy for effecting a separation between the good and the bad, if Churches do their duty. As to strangers, the Christians at Corinth had no jurisdiction, and they could not restrain their dissolute manner of life. Hence they must of necessity have quitted the world, if they wished to avoid the society of the wicked, whose vices they could not cure. For my own part, as I do not willingly adopt interpretations which cannot be made to suit the words, otherwise than by twisting the words so as to suit them, I prefer one that is different from all these, taking the word rendered to go out as meaning to be separated, and the term world as meaning the pollutions of the world "What need have you of an injunction as to the children of this world, (Luke 16:8,) for having once for all renounced the world, it becomes you to stand aloof from their society; for the whole world lieth in the wicked one." [2] (1 John 5:19.) If any one is not satisfied with this interpretation, here is still another that is probable: "I do not write to you in general terms, that you should shun the society of the fornicators of this world, though that you ought to do, without any admonition from me." I prefer, however, the former; and I am not the first contriver of it, but, while it has been brought forward previously by others, I have adapted it more fully, if I mistake not, to Paul's thread of discourse. There is, then, [3] a sort of intentional omission, when he says that he makes no mention of those that are without, inasmuch as the Corinthians ought to be already separated from them, that they may know that even at home [4] they required to maintain this discipline of avoiding the wicked.

Footnotes

1 - "The rendering of Erasmus is as follows: "Alioqui utinam videlicet e mundo exissetis;" -- "Otherwise I would, truly, that you had departed out of the world."

2 - "Car tout le monde est mis a mal;" -- "For the whole world is addicted to evil."

3 - "En ceste sentence;" -- "In this sentence."

4 - "C'est a dire, entr'eux;" -- "That is to say, among themselves."

Yet not altogether - In my direction not "to company" with them, I did not mean that you should refuse all kinds of contact with them; that you should not treat them with civility, or be engaged with them in any of the transactions of life, or in the ordinary contact of society between man and man, for this would be impossible - but that you should not so associate with them as to be esteemed to belong to them, or so as to be corrupted by their example. You are not to make them companions and friends.
With the fornicators - Most pagans were of this description, and particularly at Corinth. See the introduction to this Epistle.
Of this world - Of those who are out of the church; or who are not professed Christians.
Or with the covetous - The avaricious; those greedy of gain. Probably his direction in the former epistle had been that they should avoid them.
Or extortioners - Rapacious persons; greedy of gain, and oppressing the poor, the needy, and the fatherless, to obtain money.
Or an idolater - All the Corinthians before the gospel was preached there worshipped idols.
Then must ye needs - It would be necessary to leave the world. The world is full of such persons. You meet them everywhere. You cannot avoid them in the ordinary transactions of life, unless you either destroy yourselves, or withdraw wholly from society. This passage shows:
(1) That that society was full of the licentious and the covetous, of idolaters and extortioners. (Compare the notes at Romans. 1.)
(2) that it is not right either to take our own lives to avoid them, or to withdraw from society and become monks; and therefore, that the whole monastic system is contrary to Christianity; and,
(3) That it is needful we should have some contact with the people of the world; and to have dealings with them as neighbors, and as members of the community. "How far" we are to have contact with them is not settled here. The general principles may be:
(1) That it is only so far as is necessary for the purposes of good society, or to show kindness to them as neighbors and as members of the community.
(2) we are to deal justly with them in all our transactions.
(3) we may be connected with them in regard to the things which "we have in common" - as public improvements, the business of education, etc.
(4) we are to endeavor to do them good, and for that purpose we are not to shun their society. But,
(5) We are not to make them our companions; or to associate with them in their wickedness, or as idolaters, or covetous, or licentious; we are not to be known as partakers with them in these things. And for the same reason we are not to associate with the frivilous in their gaiety; with the proud in their pride; with the fashionable in their regard to fashion; with the friends of the theater, the ballroom, or the splendid party, in their attachment to these amusements. In all these things we are to be separate; and are to be connected with them only in those things which we may have "in common" with them; and which are not inconsistent with the holy rules of the Christian religion.
(6) we are not so to associate with them as to be corrupted by their example; or so as to be led by that example to neglect prayer and the sanctuary, and the deeds of charity, and the effort to do good to the souls of people. We are to make it a great point that our piety is not to suffer by that contact; and we are never to do anything, or conform to any custom, or to have any such contact with them as to lessen our growth in grace; to divert our attention from the humble duties of religion; or to mar our Christian enjoyment.

For then must ye needs go out of the world - What an awful picture of the general corruption of manners does this exhibit! The Christians at Corinth could not transact the ordinary affairs of life with any others than with fornicators, covetous persons, extortioners, railers, drunkards, and idolaters, because there were none others in the place! How necessary was Christianity in that city!

Yet not (h) 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.
(h) If you should utterly abstain from such men's company, you should go out of the world. Therefore I speak of those who are in the very bosom of the Church, who must be brought back into order by discipline, and not of those who are outside of the Church, with whom we must labour by all means possible, to bring them to Christ.

Yet not altogether with the fornicators of this world,.... By "the fornicators of this world" are meant, such as were guilty of this sin, who were the men of the world, mere worldly carnal men, who were never called out of it, or ever professed to be; in distinction from those that were in the church, that had committed this iniquity; and the apostle's sense is, that his former prohibition of keeping company with fornicators was not to be understood as referring to such persons as were, out of the church, as if no sort of civil conversation and commerce were to be had with men of such, and the like infamous characters; or with the covetous, or extortioners, or with idolaters: that is, of this world; for this clause is to be understood of each of these; so we read (n) of , "the covetous of the world"; by the covetous are meant, either such who are given up to inordinate lusts, who work all uncleanness with greediness, and can never be satisfied with their filthy enjoyments; or such who are greedily desirous of riches and wealth, and of increasing their worldly substance by any method, right or wrong; and who not only withhold that which is meet from others, but will not allow themselves what is proper and necessary: "extortioners" are either "ravishers", as the word may be rendered: such who by force violate the chastity of others, youths or virgins; or robbers, who, by violence and rapine, take away that which is the fight and property of others; or such who oppress the poor, detain their wages by fraud, or lessen them, and extort that by unlawful gain, which is unreasonable: idolaters are those who worship the false deities of the Heathens, or any idol, graven image, or picture of God, or men, or any creature whatsoever, or any but the one Lord God. The apostle, under these characters, comprises all manner of sin against a man's self, against his neighbour, and against God; against himself, as fornication; against his neighbour, as covetousness and extortion; and against God, as idolatry: and since the world abounded with men guilty of these several vices, all kind of civil correspondence with them could not be avoided,
for then must you needs go out of the world; meaning not out of Greece, or of any of the cities thereof, into other parts, but out of the world itself; they must even destroy themselves, or seek out for a new world: it is an hyperbolical way of speaking, showing that the thing is impracticable and impossible, since men of this sort are everywhere; and were all trade and conversation with them to be forbidden, the families of God's people could never be supported, nor the interest of religion maintained; a stop would soon be put to worldly business, and saints would have little or nothing to do in the world; wherefore, as the Arabic version reads it, "business would compel you to go out of the world".
(n) Zohar in Exod. fol. 31. 2.

Limitation of the prohibition alluded to in 1-Corinthians 5:9. As in dissolute Corinth to "company with no fornicators," &c., would be almost to company with none in the (unbelieving) world; ye need not utterly ("altogether") forego intercourse with fornicators, &c., of the unbelieving world (compare 1-Corinthians 10:27; John 17:15; 1-John 5:18-19). As "fornicators" sin against themselves, so "extortioners" against their neighbors, and "idolaters" against God. The attempt to get "out of the world," in violation of God's will that believers should remain in it but keep themselves from its evil, led to monasticism and its consequent evils.

But I did not mean that you should altogether refrain from conversing with heathens, though they are guilty in some of these respects. Covetous, rapacious, idolaters - Sinners against themselves, their neighbour, God. For then ye must go out of the world - Then all civil commerce must cease. So that going out of the world, which some account a perfection, St. Paul accounts an utter absurdity.