The third time I am coming ( τριτον ερχομα ). Either the third that he had planned to come or that he had been twice. The warning is made by quoting De 19:15.

As when I was present the second time ( ως παρων το δευτερον ). This translation assumes the second visit as already made. It is a natural way to take the Greek  ως παρων. But  ως with  παρων can also mean "as if present" the second time (Authorized Version). Probably "as when" is the more natural rendering, but the other cannot be ruled entirely out in view of 1:15-23.

If I come again ( εαν ελθω εις το παλιν ). Condition of third class. The use of  παλιν of itself suits the idea that Paul had not yet made the second visit as it means simply "again" or "back," but in Mt 26:44 we find  παλιν εκ τριτου (again a third time) and so it is not decisive.

A proof of Christ ( δοκιμην του Χριστου ). He will give it to them. "I will not spare." He will show that Christ speaks "in me" ( εν εμο ).

But we shall live with him through the power of God ( αλλα ζησομεν συν αυτω εκ δυναμεως θεου ). So real is Paul's sense of his union with Christ.

Unless indeed ye be reprobate ( ε μητ αδοκιμο εστε ). Paul challenged his opposers in Corinth to try ( πειραζετε ) themselves, to test ( δοκιμαζετε ) themselves, whether they were "in the faith" ( εν τη πιστε ), a much more vital matter for them than trying to prove Paul a heretic. Such tests can be made, unless, alas, they are "reprobate" ( αδοκιμο, the very adjective that Paul held up before himself as a dreadful outcome to be avoided, 1Co 9:27).

That ye shall know ( οτ επιγνωσεσθε ). Such a testing of themselves will give them full knowledge that Paul is not

reprobate ( αδοκιμος ). The best way for vacillating Christians to stop it is to draw close to Christ.

Though we be as reprobate ( ημεις δε ως αδοκιμο ωμεν ). Literally, "And that" ( ινα δε ). Paul wishes them to do no wrong ( κακον μηδεν ). He has no desire to exercise his apostolic authority and "appear approved" ( δοκιμο φανωμεν, second aorist passive subjunctive of  φαινω ). He had far rather see them do "the noble thing" ( το καλον ) even if it should make him appear disapproved after all that he has said.

Against the truth ( κατα της αληθειας ). He means in the long run. We can hinder and hold down the truth by evil deeds (Ro 1:18), but in the end the truth wins.

For we rejoice ( χαιρομεν γαρ ). Paul had far rather be weak in the sense of failing to exercise his apostolic power because they did the noble thing. He is no Jonah who lamented when Ninevah repented.

Your perfecting ( υμων καταρτισιν ). Late word from  καταρτιζω, to fit, to equip (see verb in verse 11). In Plutarch, only here in N.T.

That I may not when present deal sharply ( ινα παρων αποτομως χρησωμα ). Late adverb from  αποτομος, curt, cut off. In N.T. only here and Tit 1:13.

With a holy kiss ( εν αγιω φιληματ ). In the Jewish synagogues where the sexes were separated, men kissed men, the women, women. This apparently was the Christian custom also. It is still observed in the Coptic and the Russian churches. It was dropped because of charges made against the Christians by the pagans. In England in 1250 Archbishop Walter of York introduced a "pax-board" which was first kissed by the clergy and then passed around. Think of the germ theory of disease and that kissing tablet!

The grace of the Lord Jesus Christ and the love of God, and the communion of the Holy Ghost, be with you all ( η χαρις του Κυριου Ιησου Χριστου κα η αγαπη του θεου κα η κοινωνια του αγιου πνευματος μετα παντων υμων ). This benediction is the most complete of them all. It presents the persons of the Trinity in full form. From 2Th 3:17 it appears that Paul wrote the greeting or benediction with his own hand. We know from Ro 15:19 that Paul went round about unto Illyricum before, apparently, he came on to Corinth. When he did arrive (Ac 20:1-3) the troubles from the Judaizers had disappeared. Probably the leaders left after the coming of Titus and the brethren with this Epistle. The reading of it in the church would make a stir of no small proportions. But it did the work.