The interpretation timeline
1 Corinthians 5:9 Douay-Rheims

I wrote to you in an epistle, not to keep company with fornicators.

A.D. 220 – 1871 8 witnesses

Patristic

before A.D. 750
220
A.D.
Tertullian Patristic
c. A.D. 150–220
“But now I write to you, if any is named a brother among you, (being) a fornicator, or an idolater" (for what so intimately joined?), "or a defrauder" (for what so near akin?), and so on, "with such to take no food even," not to say the Eucharist: because, to wit, withal "a little leaven spoileth the flavour of the whole lump.”
Source
407
A.D.
John Chrysostom Patristic
A.D. 347–407
“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. "But now I write unto you, If any brother" be of this kind, "with such an one no not to eat." Here also he glances at others who were living in wickedness. But how can one "that is a brother" be an idolater? As was the case once in regard to the Samaritans who chose piety but by halves. And besides he is laying down his ground beforehand for the discourse concerning things offered in sacrifice to idols, which after this he intends to handle. "Or covetous." For with these also he enters into conflict. Wherefore he said also, "Why not rather take wrong? Why not rather be defrauded? Nay, ye yourselves do wrong and defraud." "Or a drunkard." For this also he lays to their charge further on; as when he says, "One is hungry and another is drunken:" and, "meats for the belly and the belly for meats." "Or a reviler, or an extortioner:" for these too he had rebuked before.”
Source

Scholastic

c. 1100 – 1500
1272
A.D.
Thomas Aquinas Catholic
1225–1274
“**On 1 Corinthians, Chapter 5, Lecture 3** Above, the Apostle had led the Corinthians to this, that they should separate the sinner from themselves, which indeed they had neglected on account of a false understanding of a certain word that was contained in a certain letter which he had sent to them earlier. And therefore he now excludes the depraved sense which they had conceived from the words. Hence concerning this he does three things. First he resumes the word of the earlier letter; second he excludes the false understanding, at the words: *not altogether with fornicators*; third he expounds the true understanding, at the words: *but now I have written to you*. He says therefore first: I said to you in a certain other letter, which is not contained in the canon, *that you should not associate with fornicators*, that is, that you should not have society or communion with them, according to that word of Prov. 1:15: *my son, walk not with them, keep back your foot from their paths*; Ecclus. 9:6: *give not your soul to fornicators in anything*. Then, when he says *not altogether with fornicators*, he excludes the false understanding of the aforesaid word. And first he sets forth what he intends; second he concludes his proposition, at the words: *otherwise you would have had to*, etc. Concerning the first, it must be considered that the Corinthians had conceived a false understanding of the aforesaid word of the Apostle in two ways. First, as to this, that they understood it to have been said of unbelieving fornicators. But the Apostle excludes this, saying *not altogether* do I intend to say that you should not associate with the fornicators of this world. Now he calls unbelievers by the name of world, according to what is said in Jn. 1:10: *the world knew him not*; above, ch. 1:21: *the world by wisdom knew not God*. Second, they had conceived a false understanding as to this, that they thought the Apostle had forbidden only concerning fornicators, but not concerning other sinners. And therefore, to exclude this, he adds *or with the covetous*, namely, those who unjustly withhold what belongs to others. Eph. 5:5: *covetousness, which is the service of idols, has no inheritance in the kingdom of Christ and of God*. *Or with the rapacious*, namely, those who violently seize what belongs to others. Below, in the same place: *nor shall the rapacious possess the kingdom of God*. *Or with those serving idols*, against whom it is said Wis. 14:27: *for the worship of unspeakable idols is the cause of all evil, its beginning and its end*. And the sense is: I have forbidden you the society not only of fornicators, but also of all other sinners. And it is to be noted that by fornication one sins against himself, but by covetousness and rapacity against one's neighbor, and by the worship of idols against God; and in these things which he sets down, every kind of sin is understood. Then, when he says *otherwise*, etc., he assigns the reason for his proposition, saying *otherwise* — namely, if the aforesaid word were to be understood of the fornicators of this world — *you would have had to go out of this world*, since the whole world is full of such people. Hence you could not avoid such fornicators, except by going out of this world. For it is said, 1 Jn. 5:19: *the whole world is set in wickedness*. Or otherwise: *you would have had to go out of this world*, as if he were saying: from the time of your conversion you ought to have been separated from the unbelievers of the world. Hence you do not need to be admonished about this; for it is said, Jn. 15:16: *I have chosen you out of the world*. Or otherwise: *you would have had to go out of this world*, namely through death. For it is better for men to die than to consent to sinners in their sins. Hence it is said below, 9:15: *for it is better for me to die, than that any man should make my glory void*. Then, when he says *but now I have written to you*, he expounds to them the true understanding, and first he sets forth what he intends; second he assigns the reason, at the words: *for what have I to do*?; third he infers the intended conclusion, at the words: *take away the evil*, etc. He says therefore first: but now I explain thus what I formerly wrote to you: *do not associate*, namely, with fornicators and other sinners, *if he who*, among you, *is called a brother*, in the way the Lord says, Matth. 23:8: *you are all brothers*. Yet he does not say: if he who is a brother, but: *if he who is called a brother*, because through mortal sin someone withdraws from charity, which is the cause of spiritual brotherhood. Hence it is said in the last chapter of Hebrews: *let the charity of brotherhood remain in you*. He is therefore called a brother on account of the truth of the faith, but he is not truly a brother, on account of the lack of charity, which comes from sin. Hence it is added *or a fornicator, or covetous, or serving idols, or a railer, or rapacious, or a drunkard, with such a one not even to take food* — namely, you ought not — according to that word of the second canonical epistle of John: *if any man come to you, and bring not this doctrine, receive him not into your house, nor say to him, hail*; as if he were saying: by this that I said you ought not to be mixed with sinners, I meant concerning the faithful who are called brothers, and are among you. But it is not to be understood by this, as Augustine says in the book against Parmenian, and as is held in the Gloss here, that someone ought to be separated from the communion of others by an extraordinary judgment, since he could frequently err, but rather this ought to be done according to the order of the Church, when someone is repelled from communion, as one convicted, or one who has confessed of his own accord. And therefore he says pointedly *if he who is called*, so that we may understand that naming to be the one which comes about through a sentence of the Church pronounced against someone in judicial order. But those who are thus expelled from communion are to be avoided as to table, as is said here, and as to greeting, as is said in the aforesaid authority of John, and further as to sacred communion. Hence it is said in the verse: *mouth, to pray, farewell, communion, table are denied* — namely, to the excommunicate. But it must be noted that the Apostle above numbered only mortal sins, as a sign that someone ought to be excommunicated only for mortal sin. And concerning the other things indeed which he sets down it is manifest; but concerning drunkenness there can be doubt, since it does not always seem to be a mortal sin. For Augustine says in the sermon on Purgatory, that drunkenness, unless it be frequent, is not a mortal sin. Which I believe to be so, because drunkenness in its own kind is a mortal sin. For that someone should wish, for the delight of wine, to lose the use of reason, exposing himself to the danger of committing many other sins, seems to be contrary to charity. It happens, however, accidentally that drunkenness is not a mortal sin, on account of ignorance of the strength of the wine, or of the weakness of one's own head — an excuse which is nevertheless removed by frequent experience: and therefore the Apostle pointedly does not say *drunk* but *a drunkard*. Now he adds two sins to those which he had set down above, namely, the drunkard and the railer. Now drunkenness is referred to the kind of sin which is committed against oneself, under which is contained not only lust, but also gluttony; but the railer is referred to the kind of sin which is committed against one's neighbor, whom someone harms not only in deed, but also in word, by wishing evil upon him, or by defaming him wrongly — which pertains to detraction — or by saying evil things to his face — which pertains to contumely — and all this pertains to the notion of a railer, as was said above. Then, when he says *for what have I to do*, etc., he assigns the reason for what he had said. And concerning this he does three things. First he assigns the reason, saying: I said this is to be understood of brothers, and not of unbelievers. *For what have I to do*, that is, what does it pertain to me, *to judge*, that is, to pronounce a sentence of condemnation, *concerning those who are outside*? That is, concerning unbelievers, who are entirely outside the Church? For the prelates of the Churches receive spiritual power only over those who have subjected themselves to the faith, according to that word of 2 Cor. 10:6: *having in readiness to revenge all disobedience, when your obedience shall be fulfilled*. Indirectly, however, the prelates of the Churches have power over those who are outside, insofar as, on account of their fault, they forbid the faithful to have communion with them. Second, he employs a comparison, saying *do you not judge those who are within*? As if he were saying: you judge by the same authority as I. Hence, just as you do not judge except concerning your own, so also I. It is said, Ecclus. 10:1: *a wise judge shall judge his people*. Third, he answers a tacit doubt. For it might seem that unbelievers were better off, since they are not condemned for the aforesaid sins; but he excludes this, saying: therefore it is nothing to me to judge concerning those who are outside, for *those who are outside*, that is, unbelievers, *God will judge*, namely by a judgment of condemnation, not of examination; because, as Gregory says in the Morals, unbelievers will be damned without a judgment of discussion and examination. And as to this it is said, Jn. 3:18: *he who does not believe is already judged*, that is, he has in himself a manifest cause of condemnation, and this is reserved more gravely to the judgment of God, according to that word of Heb. 10:31: *it is a fearful thing to fall into the hands of the living God*. Then, when he says *take away the evil*, etc., he infers the conclusion principally intended, saying: since this which I said, *do not associate with fornicators*, is to be understood of the faithful, not of those who are outside — therefore *take away the evil*, namely, the man, *from among yourselves*, that is, cast him out of your society, according to that word of Deut. 13:5: *you shall take away the evil from the midst of you*. It must therefore be considered, from the aforesaid words of the Apostle, that we are not forbidden to have communion with unbelievers who never received the faith, on account of their punishment. This must, however, be guarded against by some, namely the weak, for their own caution, lest they be seduced. But those who are firm in the faith can lawfully communicate with them, and give effort to their conversion, as is said below, 10:27: *if any of the unbelievers invite you to a feast, and you are willing to go, eat whatever shall be set before you*. But from unbelievers who were at one time faithful, or who received the sacrament of the faith, such as heretics and those apostatizing from the faith, the communion of the faithful is entirely withdrawn, and this as their punishment, just as also for the other sinners who are still subject to the power of the Church.”

Post-Reformation

c. 1650 – 1900
1714
A.D.
Matthew Henry Reformed
1662–1714
“Here the apostle advises them to shun the company and converse of scandalous professors. Consider, I. The advice itself: I wrote to you in a letter not to company with fornicators, Co1 5:9. Some think this was an epistle written to them before, which is lost. Yet we have lost nothing by it, the Christian revelation being entire in those books of scripture which have come down to us, which are all that were intended by God for the general use of Christians, or he could and would in his providence have preserved more of the writings of inspired men. Some think it is to be understood of this very epistle, that he had written this advice before he had full information of their whole case, but thought it needful now to be more particular. And therefore on this occasion he tells them that if any man called a brother, any one professing Christianity, and being a member of a Christian church, were a fornicator, or covetous, or an idolater, or a railer, that they should not keep company with him, nor so much as eat with such a one. They were to avoid all familiarity with him; they were to have no commerce with him; they were to have no commerce with him: but, that they might shame him, and bring him to repentance, must disclaim and shun him. Note, Christians are to avoid the familiar conversation of fellow-christians that are notoriously wicked, and under just censure for their flagitious practices. Such disgrace the Christian name. They may call themselves brethren in Christ, but they are not Christian brethren. They are only fit companions for the brethren in iniquity; and to such company they should be left, till they mend their ways and doings. II. How he limits this advice. He does not forbid the Christians the like commerce with scandalously wicked heathens. He does not forbid their eating nor conversing with the fornicators of this world, etc. They know no better. They profess no better. The gods they serve, and the worship they render to many of them, countenance such wickedness. "You must needs go out of the world if you will have no conversation with such men. Your Gentile neighbours are generally vicious and profane; and it is impossible, as long as you are in the world, and have any worldly business to do, but you must fall into their company. This cannot be wholly avoided." Note, Christians may and ought to testify more respect to loose worldlings than to loose Christians. This seems a paradox. Why should we shun the company of a profane or loose Christian, rather than that of a profane or loose heathen? III. The reason of this limitation is here assigned. It is impossible the one should be avoided. Christians must have gone out of the world to avoid the company of loose heathens. But this was impossible, as long as they had business in the world. While they are minding their duty, and doing their proper business, God can and will preserve them from contagion. Besides, they carry an antidote against the infection of their bad example, and are naturally upon their guard. They are apt to have a horror at their wicked practices. But the dread of sin wears off by familiar converse with wicked Christians. Our own safety and preservation are a reason of this difference. But, besides, heathens were such as Christians had nothing to do to judge and censure, and avoid upon a censure passed; for they are without (Co1 5:12), and must be left to God's judgment, Co1 5:13. But, as to members of the church, they are within, are professedly bound by the laws and rules of Christianity, and not only liable to the judgment of God, but to the censures of those who are set over them, and the fellow-members of the same body, when they transgress those rules. Every Christian is bound to judge them unfit for communion and familiar converse. They are to be punished, by having this mark of disgrace put upon them, that they may be shamed, and, if possible, reclaimed thereby: and the more because the sins of such much more dishonour God than the sins of the openly wicked and profane can do. The church therefore is obliged to clear herself from all confederacy with them, or connivance at them, and to bear testimony against their wicked practices. Note, Though the church has nothing to do with those without, it must endeavour to keep clear of the guilt and reproach of those within. IV. How he applies the argument to the case before him: "Therefore put away from among yourselves that wicked person, Co1 5:13. Cast him out of your fellowship, and avoid his conversation."”
Source
1771
A.D.
John Gill Reformed
1697–1771
“I wrote unto you in an epistle,..... Not in this same epistle, and in Co1 5:2 as some think; for what is here observed is not written in either of those verses, but in some other epistle he had sent them before, as is clear from Co1 5:11 which either came not to hand, or else was neglected by them; and so what he here says may be considered as a reproof to them, for taking no notice of his advice; but continuing to show respect to the incestuous person, though he in a former epistle had advised them to the contrary: no doubt the apostle wrote other epistles to the Corinthians, besides those that are in being; see Co2 10:10 nor does such a supposition at all detract from the perfection of Scripture; for not all that were written by him were by divine inspiration; and as many as were so, and were necessary for the perfection of the canon of Scripture, and to instruct us in the whole counsel of God, have been preserved; nor is this any contradiction to this epistle's being his first to this church; for though it might not be his first to them, yet it is the first to them extant with us, and therefore so called: what he had written to them in another epistle was not to company with fornicators; which he had not so fully explained, neither what fornicators he meant, nor what by keeping company with them; he therefore in this distinguishes upon the former, and enlarges his sense of the latter; declaring that they were not so much as to eat with such persons; which shows, that this prohibition does not regard unclean copulation, or a joining with them in the sin of fornication, they had been used to in a state of unregeneracy, for some sort of companying with fornicators is allowed of in the next verse; whereas no degree of a sinful mixture with them would ever be tolerated: but that it is to be understood of a civil society and familiar conversation with them; which might bring a reproach upon religion, be a stumbling to weak Christians, and be of dangerous consequence to themselves and others; who hereby might be allured and drawn by their example into the commission of the same sinful practices. The apostle seems to allude to the customs and usages of the Jews, who abstained from all civil commerce and familiar acquaintance with unbelievers. They say, "that everyone that does not study in the law, , "it is forbidden to come near him, and to exercise merchandise with him, and much less to walk with him in the way", because there is no faith in him (m).'' (m) Zohar in Lev. fol. 33. 2.”
Source
1832
A.D.
Adam Clarke Methodist
1762–1832
“I wrote unto you in an epistle - The wisest and best skilled in Biblical criticism agree that the apostle does not refer to any other epistle than this; and that he speaks here of some general directions which he had given in the foregoing part of it; but which he had now in some measure changed and greatly strengthened, as we see from Co1 5:11. The words εγραψα εν τῃ επιστολῃ may be translated, I Had written to you in This Epistle; for there are many instances in the New Testament where the aorist, which is here used, and which is a sort of indefinite tense, is used for the perfect and the plusquam-perfect. Dr. Whitby produces several proofs of this, and contends that the conclusion drawn by some, viz. that it refers to some epistle that is lost, is not legitimately drawn from any premises which either this text or antiquity affords. The principal evidence against this is Co2 7:8, where εν τῃ επιστολῃ, the same words as above, appear to refer to this first epistle. Possibly the apostle may refer to an epistle which he had written though not sent; for, on receiving farther information from Stephanas, Fortunatus, and Achaicus, relative to the state of the Corinthian Church, he suppressed that, and wrote this, in which he considers the subject much more at large. See Dr. Lightfoot. Not to company with fornicators - With which, as we have already seen, Corinth abounded. It was not only the grand sin, but staple, of the place.”
Source
1849
A.D.
1774–1849
“&c. I wrote to you in an epistle. If he does not mean what he has said already in this epistle, it must have been in some other, which he had written to them before, (as some conjecture) and which is not now extant. — Now to keep company with fornicators, nor with such like public scandalous sinners, not so much as to eat with them. But you must take notice, that I mean, when they are brethren, or Christians, not when they are infidels, for this cannot be avoided, especially by those who are to labour to convert them. This admonition of the apostle, shews us how much such persons are to blame, who by their carriage encourage, applaud, and are delighted with wicked company. Them who are without the pale and fold of the Church, the apostle leaves to the great judge of the living and the dead. (Witham)”
Source
1871
A.D.
1871
“I wrote . . . in an epistle--rather, "in the Epistle": a former one not now extant. That Paul does not refer to the present letter is proved by the fact that no direction "not to company with fornicators" occurs in the previous part of it; also the words, "in an (or, the) epistle," could not have been added if he meant, "I have just written" (Co2 10:10). "His letters" (plural; not applying to merely one) confirm this. Co2 7:8 also refers to our first Epistle, just as here a former letter is referred to by the same phrase. Paul probably wrote a former brief reply to inquiries of the Corinthians: our first Epistle, as it enters more fully into the same subject, has superseded the former, which the Holy Spirit did not design for the guidance of the Church in general, and which therefore has not been preserved. See my Introduction.”
Source
Modern · 1953 →

The in-app commentary runs from the Fathers to the early-modern record, then stops — that's where the public-domain sources end, not where the reading does. For the modern reading, follow the sources directly.