God forbid (there is no better English phrase for expressing the indignant repudiation of μὴ γένοιτο): yea, let God be true ( γινέσθω ἀληθὴς; i.e. "let his truth be established;" "Fiat, in judicio," Bengel), but every man a liar; as it is written, That thou mightest be justified in thy sayings, and mightest overcome when thou art judged, We can hardly avoid recognizing a reference to Psalms 116:11 in "every man a liar, the words of the LXX. being exactly given, though the general purport of that psalm does not bear upon the present argument. The apostle takes this phrase from it as expressing well what he wants to say, viz. that though all men were false (in the sense expressed and implied by the previous ἠπίστησαν), yet God's truth stands. But it only leads up to the second quotation from Psalms 51:1-19., which is the important one, introduced by καθὼς γέραπται. In its final words, νικήσης ἐν τῶ κρίνεσθαί σε, the LXX. is followed (so also Vulgate, cum judicaris), though the Hebrew may be more correctly rendered, as in the Authorized Version, "be clear when thou judgest." The κρίνεσθαι of the LXX. may be understood passively in the sense of God being called to account, as men might be, for the justice of his dealings; or, perhaps, in a middle sense for entering into a suit or controversy with his people. κρίνεσθαι means "going to law" in 1 Corinthians 6:1, 1 Corinthians 6:6 (cf. also Matthew 5:40), and in the LXX., with especial reference to a supposed controversy or pleading of God with men, Jeremiah 25:31; Job 9:2; Job 13:19. (See also Hosea 2:2, κρίθητε πρὸς τὴν μητέρα ὑῶν.) The meaning of this concluding expression does not, however, affect the main purport of the verse, or its relevancy as here quoted. Occurring in what is believed to be David's penitential psalm after his sin. in the matter of Uriah, it declares, in conjunction with the preceding verse, that, sin having been committed, man alone is guilty, and that God's truth and righteousness can never be impugned. But it seems to imply still more than this, viz. that man's sin has the establishment of God's righteousness as its consequence, or even, it may be, as its purpose; for the conclusion of Job 13:4 in the psalm, naturally connected with "against thee only have I sinned" preceding, is so connected by ὄπως ἂν (in Hebrew, נעַמַלְ); and it is not out of keeping with scriptural doctrine that David should have intended to express even Divine purpose in that he had been permitted, for his sins, to fall into that deeper sin with the view of establishing God's righteousness all the more. It does not, however, seem certain that the conjunction need of necessity be understood as relic; it may be embatic only. However this be, it is the inference from ὄπως ἀν that suggests the new objection of the following verse.
But if our unrighteousness commend the righteousness of God, what shall We say? Is God unrighteous who taketh vengeance? (so the Authorized Version; rather, brings the wrath upon us ( ὁ ἐπιφέρων τὴν ὀργήν), with reference to the Divine wrath against sin, spoken of above). I speak after the manner of men. God forbid: for then how shall God judge the world! The purport of this reply appears sufficiently in the paraphrase given above. But the intended Bearing on the argument of Romans 3:7 is not at once apparent.