John Calvin Commentary Romans 2:15

"in that they show the work of the law written in their hearts, their conscience bearing witness therewith, and their thoughts one with another accusing or else excusing [them]);" — Romans 2:15 (ASV)

Who show the work of the law written, etc.; that is, they prove that there is imprinted on their hearts a discernment and judgment by which they distinguish between what is just and unjust, between what is honest and dishonest. He does not mean that it was so engraved on their will that they sought and diligently pursued it, but that they were so mastered by the power of truth that they could not disapprove of it. For why did they institute religious rites, unless they were convinced that God ought to be worshipped? Why were they ashamed of adultery and theft, unless they considered them evils?

Without reason then is the power of the will deduced from this passage, as though Paul had said that the keeping of the law is within our power; for he does not speak of the power to fulfill the law, but of the knowledge of it. Nor is the word heart to be taken for the seat of the affections, but only for the understanding, as it is found in Deuteronomy 29:4, The Lord hath not given thee a heart to understand; and in Luke 24:25, O foolish men, and slow in heart to believe.

Nor can we conclude from this passage that there is in men a full knowledge of the law, but only that there are some seeds of what is right implanted in their nature. This is evidenced by such acts as these: all the Gentiles alike instituted religious rites, they made laws to punish adultery, theft, and murder, and they commended good faith in bargains and contracts.

They have thus indeed proved that God ought to be worshipped, that adultery, theft, and murder are evils, and that honesty is commendable.

It is not relevant for us to inquire what sort of God they imagined Him to be, or how many gods they devised; it is enough to know that they thought that there is a God, and that honor and worship are due to Him. It does not matter whether they permitted the coveting of another man’s wife, or of his possessions, or of anything that was his, — whether they connived at wrath and hatred — since it was not right for them to covet what they knew to be evil when done.

Their conscience at the same time attesting, etc. He could not have urged them more forcibly than by the testimony of their own conscience, which is equal to a thousand witnesses. By the consciousness of having done good, men sustain and comfort themselves; those who are conscious of having done evil are inwardly harassed and tormented. From this came these sayings of the pagans: “A good conscience is the widest sphere; but a bad one is the cruelest executioner, and more fiercely torments the ungodly than any furies can do.” There is then a certain knowledge of the law by nature, which says, “This is good and worthy of being desired; that ought to be abhorred.”

But observe how intelligently he defines conscience: he says that reasons come to our minds by which we defend what is rightly done, and that there are those which accuse and reprove us for our vices. He refers this process of accusation and defense to the day of the Lord; not that it will then first commence, for it is now continually carried on, but that it will then also be in operation. He says this so that no one should disregard this process, as though it were vain and evanescent. And he has put, in the day, instead of, at the day, — a similar instance to what we have already observed.