In the Baptist church of my childhood, we often sang the hymn “He Paid a Debt He Did Not Owe”:

He paid a debt he did not owe
I owed a debt I could not pay
I needed someone to wash my sins away
And now I sing a brand new song
Amazing Grace all day long
Christ Jesus paid a debt that I could never pay
At the time, I was unaware that I was bearing witness to a truth about the natural law: My conscience told me that things were not as they ought to be—that I “owed a debt I could not pay”—and ultimately pointed me to Jesus Christ.

Natural law theory has received renewed attention among Protestants in recent years. The natural law tradition posits that a God-given, self-evident universal moral order exists that human reason can grasp. The natural law defines and identifies which actions are reasonable and worth pursuing—even apart from an immediate appeal to divine revelation.

In Romans 2:15, St. Paul refers to the “law written on the heart”—scriptural evidence that God has implanted in man a moral order of moral goods that acts of reason can discover. However, Paul goes on to write of sinful agents “who by their unrighteousness suppress the truth” (Rom. 1:18). This raises a question: How sufficient is the account of morality written on man’s heart?

The Bible declares that enough of the moral law obtains in our conscience that we are “without excuse” (Rom. 1:20, 32). In other words, the Bible insists that our knowledge of the moral law—and our violation of it—renders us guilty before God. “Without excuse” means the account of morality within each of us is sufficient to tell us we have done wrong. Our conscience is pricked when we lie, cheat, steal, and lust.

The existence of such a law points to the existence of a divine lawgiver. As Aquinas said, “law is an ordinance of reason, by the proper authority, for the common good, and promulgated.” Christians believe that a divine creator has ordered a universal common good and promulgated that good through a natural law in “the things that have been made” (Rom. 1:20).

The natural law, then, is the backdrop to the gospel. Our awareness of our violation of the natural law is rooted in what Aquinas calls the eternal law, which renders us guilty before a holy God. According to the Bible, each person knows he has sinned because of his conscience, even those persisting in unbelief. The Bible has no account of atheism. It only accounts for those who suppress what is self-evident by nature. Conversion thus requires recognizing the binding authority of the moral law, which indicts us and points us to our need for a Savior.

Many Christians came to know Christ not in triumph, but in a state of misery. Some may have come to Christ through intellectual pursuits, but the intellectuals I know who have submitted to Christ have done so out of an aching sense of their insufficiency and personal disarray. The pangs of conscience made each of us realize our pitiful lot. Yet we sinned not against the law as a mere abstraction, but against a lawgiver who became incarnate (John 1:1-3; Col. 1:15-17). Christ, we read, “is the end of the law.” Christ calls himself the “Way, the Truth, and the Life” (John 14:6). The grain of the universe is not an impersonal force, but is wisdom and law personified. Natural law, then, is Christotelic. Christ upholds the natural law and is its terminus (Rom. 10:4).

Paul declares to a pagan audience in Acts 17:30–31 that “the times of ignorance God overlooked, but now he commands all people everywhere to repent, because he has fixed a day on which he will judge the world in righteousness by a man whom he has appointed; and of this he has given assurance to all by raising him from the dead.” Paul is not excusing unbelief or allowing ignorance to go unchecked. Instead, Paul’s sermon is a call for the pagans to worship in full knowledge the being they worship as an “unknown God.” Paul explains that the world is held together by an incarnate Logos.

An appreciation for the general revelation of natural law is essential if we are to take the gospel to the world. The natural law is an essential pillar in a Christian ethic that hopes to be faithful to the gospel in its public witness. To borrow an idea from Carl F. H. Henry, the natural law allows us to communicate the criteria of God’s righteous judgment and the standards of morality that society must uphold if it hopes to flourish. Jettisoning the natural law means not only rejecting God, but rejecting all precepts foundational to stable social order. It is to both fronts that Christian witness is called.

Romans 1 and 2, the chapters of Scripture most often cited in regards to the natural law and our guilt before it, come just before the chapter that tells of what God has done for us in Christ: “justified by his grace as a gift, through the redemption that is in Christ Jesus, whom God put forward as a propitiation by his blood, to be received by faith” (Rom. 3:24-25). Natural law is the remnant morality that endures because of God’s common grace. But it points us to saving grace.

Editors’ note: This article originally appeared at First Things.