John Calvin Commentary Romans 4:20

"yet, looking unto the promise of God, he wavered not through unbelief, but waxed strong through faith, giving glory to God," — Romans 4:20 (ASV)

Nor did he through unbelief make an inquiry, etc. Though I do not follow the old version, nor Erasmus, yet my rendering is not given without reason. The Apostle seems to have had this in view—that Abraham did not try to find out, by weighing the matter in the balance of unbelief, whether the Lord was able to perform what he had promised.

Properly, to inquire or to search into anything is to examine it through doubt or mistrust, and to be unwilling to admit what does not appear credible without thoroughly sifting it. Abraham indeed asked how it could happen, but that was the asking of one astonished; as was the case with the virgin Mary when she inquired of the angel how what he had announced could be. And there are other similar instances.

The saints, then, when a message is brought to them respecting the works of God, the greatness of which exceeds their comprehension, do indeed burst forth into expressions of wonder; but from this wonder they soon pass on to grasp the power of God. On the contrary, the wicked, when they examine a message, scoff at and reject it as a fable. Such, as you will find, was the case with the Jews when they asked Christ how he could give his flesh to be eaten. For this reason, Abraham was not reproved when he laughed and asked how a child could be born to a man a hundred years old and to a woman of ninety; for in his astonishment he fully admitted the power of God’s word. On the other hand, a similar laughter and inquiry on the part of Sarah were not without reproof, because she did not regard the promise as valid.

If these things are applied to our present subject, it will be evident that the justification of Abraham had no other beginning than that of the Gentiles. Hence the Jews reproach their own father if they exclaim against the call of the Gentiles as something unreasonable.

Let us also remember that our condition is the same as Abraham's. All things around us are in opposition to the promises of God: He promises immortality; we are surrounded with mortality and corruption. He declares that he counts us just; we are covered with sins. He testifies that he is gracious and kind to us; outward judgments threaten his wrath. What then is to be done? We must, with closed eyes, look beyond ourselves and all things connected with us, so that nothing may hinder or prevent us from believing that God is true.

But he was strengthened, etc. This has the same meaning as a former clause, when it is said that he was not weak in faith. It is as though he had said that he overcame unbelief by the constancy and firmness of faith. Indeed, no one emerges victorious from this contest except the one who borrows weapons and strength from the word of God. From what he adds, giving glory to God, it must be observed that no greater honor can be given to God than by faith to seal his truth; as, on the other hand, no greater dishonor can be done to him than to refuse his offered favor or to discredit his word. Therefore, the most important part of honoring God is to embrace his promises obediently; and true religion begins with faith.