Even unbelievers know that God exists — despite how much they try to deny it. When they look around at his creation, he is revealed to them through the glory of his handiwork. As Paul put it, the visible testifies to the existence of the invisible. (Rom. 1:20) In other ways, still, they know the truth in their hearts because they, despite their rebellion, can loosely grasp right and wrong because the work of the law is written on their hearts.
There is a distinction to be noted here: the “work of the law” is written on the hearts of unbelievers:
For when Gentiles, who do not have the law, by nature do what the law requires, they are a law to themselves, even though they do not have the law. They show that the work of the law is written on their hearts, while their conscience also bears witness, and their conflicting thoughts accuse or even excuse them on that day when, according to my gospel, God judges the secrets of men by Christ Jesus. (Rom 2:14-16)
“The law” is written on the hearts of God’s covenant people:
For this is the covenant that I will make with the house of Israel after those days, declares the LORD: I will put my law within them, and I will write it on their hearts. And I will be their God, and they shall be my people. (Jeremiah 31:33, Heb. 10:16 )
What’s the difference between the two?
Paul tells us that, though the Gentiles did not have the law itself, they by nature do the things required by God’s law. (Rom. 2:14-16) “By nature” means that internally everyone knows certain basic tenants of the law, and they are compelled by impulse to follow them. That’s not to say that all unbelievers interpret the things required by the law the same, but their consciences do prick and prod them along (Rom. 2:15).
By grace, even unbelievers can grope around in the muddled haze of their darkened minds, in the absence of the light of life, and extract a principle of righteousness from time to time — covered in slimey filth, though it may be.
COMMON GRACE, A BLESSING AND A CURSE
It’s for the benefit of his people that God extends his common grace to unbelievers. In doing so, he restrains the depths to which they would otherwise plunge into their most depraved desires.
Because of the work of the law written on their hearts, even lawless men are compelled by their inner consciences to live by some rule of law. This is a blessing to them, for such men can build societies and prosper for a time. But by this blessing, their doing of the things which the law requires betrays their knowledge of the law and the existence of its Creator, and “so that every mouth may be stopped, and the whole world may be held accountable to God,” it condemns them (Rom. 3:19).
As Calvin wrote, the unbelievers show by their actions that “ignorance is in vain pretended as an excuse” because “they prove by their own deeds that they have some rule of righteousness.” There is no nation of men that has so abandoned its humanity that “it does not keep within the limits of some laws. Since then all nations, of themselves and without a monitor, are disposed to make laws for themselves, it is beyond all question evident that they have some notions of justice and rectitude.”
Dr. John Murray of Westminster Theological Seminary wrote that “the work of the law” is to “be taken collectively and practically equivalent to ‘the things of the law,'” which are mentioned in verse 14 of Romans 2. He said that “‘The things of the law’ must mean certain things which the law prescribes,” and they “refer to those things practised by pagans which are stipulated in the law, such as the pursuit of lawful vocations, the procreation of offspring, filial and natural affection, the care of the poor and sick, and numerous other natural virtues which are required by the law.”
ONLY ONE LAW, ONLY ONE STANDARD
Additionally, the “law” referred to is not some other law apart from that set forth in Scripture; it is not some law whose rules and stipulations are different from God’s. “The law referred to is definite and can be none other than the law of God specified in the preceding verses as the law which the Gentiles in view did not have, the law the Jews did have and under which they were, the law by which men will be condemned in the day of judgment.” [Murray, Commentary on Romans, Chapter 2]
Dr. Murray captures perhaps the biggest difference between the Gentiles who had the “work” of the law written on their hearts and the believers who had “the law” written on their hearts. He said that “such expressions as ‘fulfilling the law’ and ‘the law written upon the heart’ are reserved for a state of heart and mind and will far beyond that predicated of unbelieveing Gentiles.”
As Calvin noted, Paul was not speaking of the power to fulfill the law, but simply the knowledge of it. It’s also not to be concluded that such men have the full knowledge of the law, but merely “some seeds of what is right implanted in their nature, evidenced by such acts as” those described by Dr. Murray above.
THE SPIRIT DWELLS IN YOU
As Christians we should “delight in the law of God” (Rom. 7:22) in our inner being, and know that “Great peace have those who love [God’s] law.” (Ps. 119:65) The law reveals sin, for “sin is lawlessness,” (1 John 3:4) and “so the law is holy, and the commandment is holy and righteous and good.” (Rom. 7:12)
Unbelievers who live in the flesh cannot submit to God’s law because their mind is hostile to God (Rom. 8:7). But as Christians, since we know that the law is spiritual (Rom. 7:14), and since the Spirit of God dwells within us, we can now set our minds “on the things of the Spirit.” (Rom. 8:5) We can now, by the Spirit of Jesus Christ who lives in us, “put to death the deeds of the body,” so that we will live. (Rom. 8:13)
This is the difference between having the law itself written on our hearts compared to merely the work of the law. As Christians, we are given the ability to progressively subdue our sinful nature through the sanctifying power given us by the Holy Spirit who dwells within us. We have the law; we know where to find it (the Bible); and we want to obey it and delight in it just as our Lord and Savior did because “whoever says he abides in him ought to walk in the same way in which he walked.” (1 John 2:6)