(Author: Bob Pratico; Originally submitted Mar 5, 2022 at Southern Seminary)

Natural Law theory affirms that God embedded His moral law into creation such that rational creatures intuitively know of its existence and can comprehend good and evil to some degree. The natural law that is implanted in creation derives from the divine eternal law that resides in the mind of God before creation and exists for all eternity. Knowledge of the natural law is part of the general revelation that is universally available to everyone, independant of special revelation. Thomas Aquinas is the best known proponent of natural law theory and defines it in The Summa Theologica this way,

… this participation of the eternal law in the rational creature is called the natural law … the light of natural reason, by which we discern what is good and what is evil, which is the function of the natural law, is nothing else than the imprint on us of the Divine Light. It is therefore evident that the natural law is nothing else than the rational creature’s participation of the eternal law.1

Regarding its origin, Haines and Fulford propose that God is in fact the “first foundation of natural law.”2 With respect to its universality, Carl F. H. Henry writes that natural law theory affirms “all human beings share a set of ethical norms and imperatives that they commonly perceive without dependence on supernatural disclosure and illumination.”3 Concerning its impact on the conscience, the reformer John Calvin remarks “it is evident that the law of God which we call moral, is nothing else than the testimony of natural law and of that conscience which God has engraven on the minds of men.”4 Wayne Grudem reflecting on the universality of natural law states “the value of the study of natural law is evident when we realize that every person ever born has been given a conscience by God and therefore has some knowledge of right and wrong.”5 We find in Genesis 1 after creation that God declared a moral judgement of “good” on His creative work, implying natural law represents a real “moral fiber” built into the Cosmos. There is in effect a moral grain to creation; the adherence to it enables and produces human flourishing.

Scripture confirms the existence of natural law. Paul argues in Rom 2 that the Gentiles (without special revelation) do what the law requires by nature because it is written on their hearts with their conscience bearing witness. The early church interpreted Rom 2:12-16 this way with Ambrosiaster commenting on v. 12 that “the gentiles are also under the judgement of the natural law.”6 Ambrose remarks on v. 14 that “Gentiles show the work of the law written in their hearts. There is therefore something like the law of God which exists in the hearts of men.”7 The Reformers also understood this passage as referring to the Natural Law. Regarding v. 14, Heinrich Bullinger observes “that which seems to have been implanted in us by God as part of our nature is therefore called the ‘law of nature’.”8 Erasmus Sarcerius notes on the same verse “while it is true that the Gentiles do not have the written law, they nevertheless do possess the law of nature.”9 There are other references to natural law in Scripture. In 1 Cor 5, Paul accuses the church at Corinth of tolerating sexual immorality of a kind that even the pagans recognize (through natural law) is morally wrong. In Genesis 12, after Abraham lies about Sarah not being his wife, the pagan Pharaoh confronts him in righteous anger over his immoral behavior.

J. Budziszewski regards natural law as “the nearest approach to the truth about the ‘law written on the heart’.”10 We see indisputable evidence of the natural law in creation all around us with every culture embodying similar laws against murder and theft. There is a universal recognition that some acts are inherently wrong and others are naturally right. As a universal, the natural law is a moral standard for everyone everywhere, both believers and unbelievers. The overwhelming vast majority of people do not worry that their neighbor is going to murder them in the middle of the night and burn down their house; people intuitively know it is wrong. As Paul reminds the Corinthian church, even the pagans know what is wrong. While the law written on the conscience may be repressed with a seared sociopathic conscience, exceptions do not invalidate the rule.

But for what purpose does the natural law function? The most important role is to drive us to the gospel by convicting us of the hopelessness of perfect obedience for “we have to know the bad news before we can grasp the good news.”11 First and foremost, the natural law convicts us of the impossibility of flawless adherence to God’s moral standards; everyone without exception fails to keep it in entirety. The natural law exposes our sin nature. Paul argues this point in Rom 2 where the natural law is a mirror to our moral corruption. Andrew Walker summarizes “The natural law, then, is the backdrop to the gospel … An appreciation for the general revelation of natural law is essential if we are to take the gospel to the world.”12 But is there any Scriptural evidence that Paul used natural law in his encounters with Gentiles? James Barr counters what he refers to as the Barthian interpretation of Paul’s address to the Athenian Areopagus in Acts 17, forcefully arguing it “shows a clear affinity with principles that would normally be counted as belonging to natural theology.”13 The natural law serves as the gateway to the gospel.

A secondary important role of natural law is the restraint of sin in the world. As already pointed out, virtually every nation embraces civil laws that are remarkably similar in nature. The universal inherent grasp of moral right and wrong is a significant restraining check on the sin nature. Given full reign to the sin nature, civilization would quickly descend into a dystopian world of anarchy. The conscience can be a powerful deterrent against wrongdoing. As Robert Baker insightfully notes, the law written on our hearts may be suppressed, but cannot be erased.14

Amidst a culture rapidly descending into paganism and rejecting Biblical revelation, natural law is a logical avenue for moral reasoning and persuasion. As such, it has obvious potential for application in missiology to open the door to the truth of the gospel. In addition, it can be a powerful ally in the public arena to combat the acceptance of immoral behavior by persuading people of its existence and convicting them. While a guilty conscience may not persuade one of the truth of the gospel, it can certainly alter behavior.
How can we effectively utilize natural law in our exercise of the Great Commission? In his contribution to the discussion on natural law, Michael E. Cochran differentiates between natural law theory and natural law fact and rightly concludes “one need not have a theory to have basic moral knowledge.”15 On his web site he argues that appealing to a decaying culture with natural law requires a certain level of skill and expertise by trained Christians and properly concludes the church needs well-catechized Christians.16 We would be wise to heed him.

1 Thomas Aquinas, The Summa Theologica, (William Benton, 1952), II-I, q. XCI, a. 2, co.
2 David Haines and Andrew Fulford, Natural Law; A Brief Introduction and Biblical Defense, (The Davenant Trust, 2017), 21, Kindle
3 Carl F. H. Henry, Natural Law And A Nihilistic Culture, First Things, Jan 1995, https://www.firstthings.com/article/1995/01/natural-law-and-a-nihilistic-culture
4 John Calvin, The Institutes Of The Christian Religion, (Bonham Norton, 2010), 130, Kindle
5 Wayne Grudem, Christian Ethics, An Introduction to Biblical Moral Reasoning, (Crossway, 2018), 96, Kindle
6 Gerald Bray (editor), Ancient Christian Commentary on Scripture, New Testament VI, Romans, (Intervarsity Press, 1998), 64
7 Bray, Ancient Christian Commentary on Scripture, 67
8 Gwenfair Walters Adams (Editor), Reformation Commentary on Scripture, New Testament VII, Romans 1-8, (Intervarsity Press, 2019), 101
9 Adams, Reformation Commentary on Scripture, 101
10 J. Budziszewsk, Written On The Heart, The Case For Natural Law, (Intervarsity Press, 1997), 10, Kindle
11 Budziszewsk, Written On The Heart,11, Kindle
12 Andrew Walker, The Gospel And The Natural Law, First Things, 2020, https://www.firstthings.com/web-exclusives/2020/12/the-gospel-and-the-natural-law
13 James Barr, Biblical Faith And Natural Theology, Chapter 2, Paul on the Areopagus (Clarendon Press, 1994), https://www.giffordlectures.org/books/biblical-faith-and-natural-theology/2-paul-areopagus
14 Robert C. Baker, Natural Law: A Lutheran Reappraisal, (Concordia Publishing House, 2011), 274, Kindle
15 Baker, Natural Law: A Lutheran Reappraisal, 274, Kindle
16 Michael E. Cochran, The Forgotten Use of the Law, July 27, 2015, http://matthewcochran.net/blog/?p=789