Romans 3:4

4. God forbid Literally, It may not be so. It is not a permissible thing. The divine name is not used in the apostle’s Greek phrase, but a divine impossibility of the thing is powerfully implied in thought.

God be true The apostle here assumes two things: First, that falsehood in God would be infinitely wrong. But, second, God is surely infinitely right, and therefore falsehood or unfaithfulness must by no manner of means be admitted of God. The apostle’s ground is not that whatever a God is supposed to do (as, for instance, commit falsehood) is right because He does it; but, it is not to be admitted that the true God the God we have will commit that wrong. The apostle does not reason that because God is absolute sovereign therefore any thing supposably done by him is made right thereby. His argument is, that God is right and holy because of all possible courses he takes, not those courses which are unholy, but just the one that is holy; and of all possible doings, He ever does and will do not that which is unrighteous, but solely and truly that which is righteous. It is one of the moral perfections of God nay, the sum of all his moral perfections that He holds himself infinitely bound to all the obligations of truth, justice, and holiness, far above what man can conceive. Hence the wisdom of our perfect trust in Him, and of our feeling that perfect self-commitment to Him is a perfect self-commitment to all goodness.

True… liar Terms used in regard to fidelity or unfaithfulness to the covenant. By let be the apostle means let it be assumed as primarily true.

Written David had transgressed against the divine covenant in the murder of Uriah. Instead of justifying himself in his unfaithfulness he proclaims himself the sinner, (Psalms 51:7,) and justifies God in inflicting evil upon himself.

Thou art judged The Divine Being (reverently be it spoken) does more than once place himself and his administration before the tribunal of man’s moral sense in order to have its rectitude tested. He allows even Abraham to assume that certain courses would not be right in the Judge of all the earth. (Genesis 18:25.) But as it became David, their sinful type, so it became the apostate Jews, to assume that in the matter of the failure of the Jewish dispensation, when justice made up its verdict, God would be found the faithful and man the traitor. To “reply against God,” therefore, (Romans 9:20,) is not (with the Arminian) to assume that a course cannot be pursued by God because it would be a wrong course; it is (as the Calvinist) to assume the wrong course to be the real one, and either to reproach God with it, or to defend God by maintaining that wrong is right, and thus pervert the very foundations of all rectitude.