Natural law

A law written on the heart

God's law did not begin at Sinai. Paul says that even Gentiles who never received the law have it written on their hearts:

Indeed, when Gentiles, who do not have the law, do by nature what the law requires, they are a law to themselves, even though they do not have the law.

Romans 2:14

Their consciences bear witness, "their thoughts either accusing or defending them" (Romans 2:15). Even those who do evil "know God’s righteous decree" (Romans 1:32). In Amos, God judges Israel's neighbours, who never had the law of Moses, for their cruelty in war (Amos 1:3). The knowledge that murder, false witness and betrayal are wrong belongs to every human being.

On the things contained in the law, Wesley comments, "The ten commandments being only the substance of the law of nature." Wesley He adds that when Gentiles do these things by nature, strictly speaking that too is by preventing grace. Natural law, then, is not a law that stands apart from God. It is the Creator's will written into his creatures, part of general revelation. ‘Nature’ here means the human nature God made, not the physical regularities of the universe.

How the church came to say it

The phrase comes from Greek and Roman philosophy, the Stoics above all, but the Fathers read it anew as the law of the Creator. Justin Martyr spoke of ‘seeds of the Word’ in every person Justin Martyr, Second Apology. Thomas Aquinas taught that natural law is the rational creature's share in God's eternal law, and that its first precept is that good is to be done and pursued and evil avoided Aquinas, Summa Theologiae.

The Reformers did not discard it. Calvin held that the moral law God gave is a testimony of the natural law and of the conscience he engraved on human minds Calvin, Institutes 4.20. But this knowledge has been darkened by sin. The Westminster Confession teaches that the light of nature shows God's goodness, wisdom and power so as to leave people without excuse, yet is not sufficient to give the knowledge necessary for salvation Westminster Confession 1.1. So God set out again on tablets of stone the law written on the heart, summed up in the Ten Commandments of the law.

Where the traditions differ

The Catholic Church makes natural law a main foundation of its moral teaching: known by reason to all people, it undergirds human dignity and rights and the justice of society Catechism of the Catholic Church. Lutheran and Reformed theologians of the sixteenth and seventeenth centuries also taught natural law as the ground of civil life and of the laws of states, and saw God upholding justice in society by common grace. Protestants stress more strongly that sin has clouded reason, so that natural law must be corrected by Scripture and can never bring anyone to salvation.

In the twentieth century some, like Karl Barth, rejected natural theology and held that God is known only through his Word given in Christ; they were wary of ethics built on natural law Barth, Church Dogmatics. Among evangelicals today, some urge Christians to speak in public in the shared terms of natural law, others to speak straight from Scripture. All agree that God has written the difference between right and wrong on the human heart. See Who decides right and wrong? and the lesson Thomas Aquinas.