Actually ( ολως ). Literally, wholly, altogether, like Latin omnino and Greek  παντως (1Co 9:22). So papyri have it for "really" and also for "generally" or "everywhere" as is possible here. See also 6:7. With a negative it has the sense of "not at all" as in 15:29; Mt 5:34 the only N.T. examples, though a common word.

It is reported ( ακουετα ). Present passive indicative of  ακουω, to hear; so literally, it is heard. "Fornication is heard of among you." Probably the household of Chloe (1:11) brought this sad news (Ellicott).

And such ( κα τοιαυτη ). Climactic qualitative pronoun showing the revolting character of this particular case of illicit sexual intercourse.  Πορνεια is sometimes used (Ac 15:20,29) of such sin in general and not merely of the unmarried whereas  μοιχεια is technically adultery on the part of the married (Mr 7:21).

As is not even among the Gentiles ( ητις ουδε εν τοις εθνεσιν ). Height of scorn. The Corinthian Christians were actually trying to win pagans to Christ and living more loosely than the Corinthian heathen among whom the very word "Corinthianize" meant to live in sexual wantonness and license. See Cicero pro Cluentio, v. 14.

That one of you hath his father's wife ( ωστε γυναικα τινα του πατρος εχειν ). "So as (usual force of  ωστε ) for one to go on having ( εχειν, present infinitive) a wife of the (his) father." It was probably a permanent union (concubine or mistress) of some kind without formal marriage like Joh 4:8. The woman probably was not the offender's mother (step-mother) and the father may have been dead or divorced. The Jewish law prescribed stoning for this crime (Le 18:8; 22:11; De 22:30). But the rabbis (Rabbi Akibah) invented a subterfuge in the case of a proselyte to permit such a relation. Perhaps the Corinthians had also learned how to split hairs over moral matters in such an evil atmosphere and so to condone this crime in one of their own members. Expulsion Paul had urged in 2Th 3:6 for such offenders.

And ye are puffed up ( κα υμεις πεφυσιωμενο εστε ). Emphatic position of  υμεις (you). It may be understood as a question. Perfect passive periphrastic indicative of the same verb  φυσιοω used already of the partisans in Corinth (4:6,19,20). Those of the same faction with this scoundrel justified his rascality.

Did not rather mourn ( κα ουχ μαλλον επενθησατε ). Possibly question also and note strong negative form  ουχ, which favours it. The very least that they could have done ( μαλλον rather than be puffed up) was to mourn for shame ( πενθεω, old verb for lamentation) as if for one dead.

That he might be taken away ( ινα αρθη ). The sub-final use of  ινα of desired result (1:15) so common in the Koine. First aorist passive subjunctive of  αιρω, to lift up, to carry off. Decent self-respect should have compelled the instant expulsion of the man instead of pride in his rascality.

For I verily ( εγω μεν γαρ ). Emphatic statement of Paul's own attitude of indignation,  εγω in contrast with  υμεις. He justifies his demand for the expulsion of the man.

Being absent ( απων ) Although absent (concessive participle) and so of  παρων though present. Each with locative case ( τω σωματι, τω πνευματ ).

Have already judged ( ηδη κεκρικα ). Perfect active indicative of  κρινω. I have already decided or judged, as though present ( ως παρων ). Paul felt compelled to reach a conclusion about the case and in a sentence of much difficulty seems to conceive an imaginary church court where the culprit has been tried and condemned. There are various ways of punctuating the clauses in this sentence in verses 3-5. It is not merely Paul's individual judgment. The genitive absolute clause in verse 4,

ye being gathered together ( συναχθεντων υμων, first aorist passive participle of  συναγω, in regular assembly)

and my spirit ( κα του εμου πνευματος ) with the assembly (he means)

and meeting in the name of our Lord Jesus ( εν τω ονοματ του Κυριου [ημων] Ιησου ) with the power of the Lord Jesus ( συν τη δυναμε του Κυριου ημων Ιησου ), though this clause can be taken with the infinitive to deliver ( παραδουνα ). It makes good syntax and sense taken either way. The chief difference is that, if taken with "gathered together" ( συναχθεντων ) Paul assumes less apostolic prerogative to himself. But he did have such power and used it against Elymas (Ac 13:8ff.) as Peter did against Ananias and Sapphira (Ac 5:1ff.).

To deliver such an one unto Satan ( παραδουνα τον τοιουτον τω Σατανα ). We have the same idiom in 1Ti 1:20 used of Hymenius and Alexander. In 2Co 12:7 Paul speaks of his own physical suffering as a messenger ( αγγελος ) of Satan. Paul certainly means expulsion from the church (verse 2) and regarding him as outside of the commonwealth of Israel (Eph 2:11f.). But we are not to infer that expulsion from the local church means the damnation of the offender. The wilful offenders have to be expelled and not regarded as enemies, but admonished as brothers (2Th 3:14f.).

For the destruction of the flesh ( εις ολεθρον της σαρκος ). Both for physical suffering as in the case of Job (Job 2:6) and for conquest of the fleshly sins, remedial punishment.

That the spirit may be saved ( ινα το πνευμα σωθη ). The ultimate purpose of the expulsion as discipline. Note the use of  το πνευμα in contrast with  σαρξ as the seat of personality (cf. 3:15). Paul's motive is not merely vindictive, but the reformation of the offender who is not named here nor in 2Co 2:5-11 if the same man is meant, which is very doubtful. The final salvation of the man in the day of Christ is the goal and this is to be attained not by condoning his sin.

Not good ( ου καλον ). Not beautiful, not seemly, in view of this plague spot, this cancer on the church. They needed a surgical operation at once instead of boasting and pride (puffed up).  Καυχημα is the thing gloried in.

A little leaven leaveneth the whole lump ( μικρα ζυμη ολον το φυραμα ζυμο ). This proverb occurs verbatim in Ga 5:9.  Ζυμη (leaven) is a late word from  ζεω, to boil, as is  ζυμοω, to leaven. The contraction is regular ( -οει=ο ) for the third person singular present indicative. See the parables of Jesus for the pervasive power of leaven (Mt 13:33). Some of the members may have argued that one such case did not affect the church as a whole, a specious excuse for negligence that Paul here answers. The emphasis is on the "little" ( μικρα, note position). Lump ( φυραμα from  φυραω, to mix, late word, in the papyri mixing a medical prescription) is a substance mixed with water and kneaded like dough. Compare the pervasive power of germs of disease in the body as they spread through the body.

Purge out ( εκκαθαρατε ). First aorist (effective) active imperative of  εκκαθαιρω, old verb to cleanse out ( εκ ), to clean completely. Aorist tense of urgency, do it now and do it effectively before the whole church is contaminated. This turn to the metaphor is from the command to purge out the old ( παλαιαν, now old and decayed) leaven before the passover feast (Ex 12:15f.; 13:7; Zep 1:12). Cf. modern methods of disinfection after a contagious disease.

A new lump ( νεον φυραμα ). Make a fresh start as a new community with the contamination removed.  Νεος is the root for  νεανισκος, a young man, not yet old ( γηραιος ). So new wine ( οινον νεον Mt 9:17).  Καινος is fresh as compared with the ancient ( παλαιος ). See the distinction in Col 3:10; Eph 4:22ff.; 2Co 5:17.

Unleavened ( αζυμο ). Without ( α privative) leaven, the normal and ideal state of Christians. Rare word among the ancients (once in Plato). They are a new creation ( καινη κτισις ), "exemplifying Kant's maxim that you should treat a man as if he were what you would wish him to be" (Robertson and Plummer).

For our passover also hath been sacrificed, even Christ ( κα γαρ το πασχα ημων ετυθη Χριστος ). First aorist passive indicative of  θυω, old verb to sacrifice. Euphony of consonants,  θ to  τ because of  -θη. Reference to the death of Christ on the Cross as the Paschal Lamb (common use of  πασχα as Mr 14:12; Lu 22:7), the figure used long before by the Baptist of Jesus (Joh 1:29). Paul means that the Lamb was already slain on Calvary and yet you have not gotten rid of the leaven.

Wherefore let us keep the feast ( ωστε εορταζωμεν ). Present active subjunctive (volitive). Let us keep on keeping the feast, a perpetual feast (Lightfoot), and keep the leaven out. It is quite possible that Paul was writing about the time of the Jewish passover, since it was before pentecost (1Co 16:8). But, if so, that is merely incidental, and his language here is not a plea for the observance of Easter by Christians.

With the leaven of malice and wickedness ( εν ζυμη κακιας κα πονηριας ). Vicious disposition and evil deed.

With the unleavened bread of sincerity and truth ( εν αζυμοις ειλικρινιας κα αληθειας ). No word for "bread." The plural of  αζυμοις may suggest "elements" or "loaves."  Ειλικρινια (sincerity) does not occur in the ancient Greek and is rare in the later Greek. In the papyri it means probity in one example. The etymology is uncertain. Boisacq inclines to the notion of  ειλη or  ελη, sunlight, and  κρινω, to judge by the light of the sun, holding up to the light.  Αληθεια (truth) is a common word from  αληθης (true) and this from  α privative and  ληθω ( λαθειν, λανθανω, to conceal or hide) and so unconcealed, not hidden. The Greek idea of truth is out in the open. Note Ro 1:18 where Paul pictures those who are holding down the truth in unrighteousness.

I wrote unto you in my epistle ( εγραψα υμιν εν τη επιστολη ). Not the epistolary aorist, but a reference to an epistle to the Corinthians earlier than this one (our First Corinthians), one not preserved to us. What a "find" it would be if a bundle of papyri in Egypt should give it back to us?

To have no company with fornicators ( μη συναναμιγνυσθα πορνοις ). Present middle infinitive with  μη in an indirect command of a late double compound verb used in the papyri to mix up with ( συν-ανα-μιγνυσθα, a  μ verb). It is in the N.T. only here and verse 11; 2Th 3:14 which see. It is used here with the associative instrumental case ( πορνοις, from  περαω, περνημ, to sell, men and women who sell their bodies for lust). It is a pertinent question today how far modern views try to put a veneer over the vice in men and women.

Not altogether ( ου παντως ). Not absolutely, not in all circumstances. Paul thus puts a limitation on his prohibition and confines it to members of the church. He has no jurisdiction over the outsiders (this world,  του κοσμου τουτου ).

The covetous ( τοις πλεονεκταις ). Old word for the over-reachers, those avaricious for more and more ( πλεον, εχω, to have more). In N.T. only here, 6:10; Eph 5:5. It always comes in bad company (the licentious and the idolaters) like the modern gangsters who form a combination of liquor, lewdness, lawlessness for money and power.

Extortioners ( αρπαξιν ). An old adjective with only one gender, rapacious (Mt 7:15; Lu 18:11), and as a substantive robber or extortioner (here and 6:10). Bandits, hijackers, grafters they would be called today.

Idolaters ( ειδωλολατραις ). Late word for hirelings ( λατρις ) of the idols ( ειδωλον ), so our very word idolater. See 6:9; 10:7; Eph 5:5; Re 21:8; 22:15. Nageli regards this word as a Christian formation.

For then must ye needs ( επε ωφειλετε ουν ). This neat Greek idiom of  επε with the imperfect indicative ( ωφειλετε, from  οφειλω, to be under obligation) is really the conclusion of a second-class condition with the condition unexpressed (Robertson, Grammar, p. 965). Sometimes  αν is used also as in Heb 10:2, but with verbs of obligation or necessity  αν is usually absent as here (cf. Heb 9:20). The unexpressed condition here would be, "if that were true" (including fornicators, the covetous, extortioners, idolaters of the outside world).  Αρα means in that case.

But now I write unto you ( νυν δε εγραψα υμιν ). This is the epistolary aorist referring to this same epistle and not to a previous one as in verse 9. As it is (when you read it) I did write unto you.

If any man that is named a brother be ( εαν τις αδελφος ονομαζομενος η ). Condition of the third class, a supposable case.

Or a reviler or a drunkard ( η λοιδορος η μεθυσος ).  Λοιδορος occurs in Euripides as an adjective and in later writings. In N.T. only here and 6:10. For the verb see 1Co 4:12.  Μεθυσος is an old Greek word for women and even men (cf.  παροινος, of men, 1Ti 3:3). In N.T. only here and 6:10. Cf. Ro 13:13. Deissmann (Light from the Ancient East, p. 316) gives a list of virtues and vices on counters for Roman games that correspond remarkably with Paul's list of vices here and in 6:10. Chrysostom noted that people in his day complained of the bad company given by Paul for revilers and drunkards as being men with more "respectable" vices!

With such a one, no, not to eat ( τω τοιουτω μηδε συνεσθιειν ). Associative instrumental case of  τοιουτω after  συνεσθιειν, "not even to eat with such a one." Social contacts with such "a brother" are forbidden

For what have I to do? ( τ γαρ μοι; ). "For what is it to me (dative) to judge those without ( τους εξο )?" They are outside the church and not within Paul's jurisdiction. God passes judgment on them.

Put away the wicked man ( εξαρατε τον πονηρον ). By this quotation from De 17:7 Paul clinches the case for the expulsion of the offender (5:2). Note  εξ twice and effective aorist tense.