Christians in America, now more than ever, find themselves in the unfamiliar position of having to reason in the public square with fellow citizens and leaders who are not convinced of the Bible’s ultimate authority. Though unfamiliar to us, this would have been nothing new for the early Church. The apostle Paul faced a similar situation in his speech to the Athenians in the latter part of Acts 17. When his audience consisted of pagan philosophers, Paul made an interesting rhetorical decision. He did not use Scripture to make his case, as he commonly did throughout his ministry (e.g. Acts 17:1-4), but instead he presented what John Wesley described as “a divinely philosophical discourse.” Unfortunately, the ability to present biblical truths without relying on Scripture is a lost art for contemporary Christians.
Compounding the problem for Christians is the fact that in today’s highly technological and developed society there are many ethical dilemmas to which the Bible is silent or only provides general principles. How can Christians intelligently engage in discussions of physician assisted suicide, in vitro fertilization, gender-specific bathrooms, drone strikes, immigration, and other pressing moral situations if the extent of their moral philosophy is citing Scripture?
The Christian community needs to commit to developing not only what they believe, but why they believe it as well. This is where the moral philosophy of natural law has historically aided the Church, and can aid her yet again. Natural law is understood to be a set of unchanging moral principles known intrinsically to all persons and discernible by a rational examination of human nature. This of course does not mean every individual has a perfectly fine-tuned moral compass, but rather that the foundational first principles of morality are intuitively known and can serve as a basis for further moral reasoning and application. Natural law also serves as a benchmark by which positive (man-made) law is evaluated. While natural law may sound like a foreign concept to today’s Christian, especially those of the Protestant or evangelical traditions (of which I am a part), it is something that was apparent throughout the Church for most of its history. Church Fathers such as Augustine and Aquinas— and even Protestant leaders such as Luther and Calvin—were all proponents of natural law.
The reason for the Church’s open embrace of natural law throughout history is that is a tradition deeply rooted in Scripture. A proper study of human nature can help to discern moral goodness because of our relation to God. Genesis 1:26 states, “Then God said, ‘Let us make man in our image, after our likeness.’” Romans 1:19-20 adds to this by also explaining that God created the world, including man, in a way that is plain and discernible. By studying what is proper for human nature and what leads to human flourishing, one is simply deducing how God intended man to live.
Furthermore, natural law is prevalent throughout the biblical narrative. A salient biblical statement on natural law comes from Romans 2:14-15, which Paul states,
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.
These principles are apparent throughout Scripture. Take for example the prophet Amos, who warned Israel and the surrounding nations of God’s impending judgment for their moral failures. What is interesting about Amos’ prophecies are the different ways in which he judged Israel versus the other nations. With Israel, Amos prophesied “I will not revoke the punishment, because they have rejected the law of the Lord”. Israel was to be punished for disobeying God’s commands given to them in the Scriptures. If deviation from the divine law is grounds for Israel’s punishment, on what grounds can God also judge the neighboring nations who have received no such written law? The answer lies with natural law. God has written the law on the hearts of all people, including the people in the surrounding nations, so they will be held responsible for their actions. The fact that they exiled entire people groups, pursued their brother with a sword, and ripped open pregnant women means they were violating the natural law and therefore justly deserving the judgment of God.
Natural law also serves the invaluable role of showing that the divine laws of Scripture are not some arbitrary set of rules given by a controlling God. Rather they are a set of laws designed to lead to ultimate human flourishing. Just as science can help us better appreciate the world in which we live by allowing us to better understand the amazing intricacies and factors found on the planet, so too can natural law help us better appreciate human nature. Sherif Girgis, a natural law theorist, expands on this idea by writing, “properly philosophical reasoning also helps the Church to spread her teachings by defending them as wise counsel, not arbitrary constraint: a fruit of divine love and not despotism.” Here Girgis shows the beautifully interdependent relationship shared by divine and natural law. If divine and natural law both stem from the same Law Giver, then it follows that the two laws will be in perfect harmony with one another. Divine law can be understood as perfect enumerations of natural law because it originates from the same eternal source. Consequently, we are able to understand natural law on a deeper level because of divine law. Natural law theorist J. Budziszewski agrees: “Even though the elementary principles of the moral law are known by nature, they are elicited, elucidated, and elaborated by tradition.” Far from undermining the authority of Scripture, natural law helps illuminate divine law by providing a rationale as to why the law commands what it does and helps to provide principles that can be applied to new and different situations. Divine and natural law are two different languages and two different approaches that express the same ultimate truth, meaning the two will never conflict with one another, but instead will build and complement each other.
A simple illustration of this in action may help. By examining human nature and what leads to human flourishing, one can properly deduce the importance of rest. Budziszewski argues “we are built to run in cycles. It isn’t possible for beings of our kind to do everything all the time.” The divine law refines this, requiring one day of rest (or a Sabbath) every week. This is how “the universal and particular are mixed,” meaning both laws contribute to a proper and fuller understanding. By using both natural and divine law, one can arrive to the conclusion that a Sabbath rest is important for human well-being; a proposition confirmed by modern science. Without the natural law, the Sabbath seems arbitrary, and without the divine law, rest remains an unconfirmed and unrefined principle of human nature that misses the ultimate telos of rest; a reordering of one’s life towards God. The greater understanding of rest brought forth by the Sabbath can only be understood by an examination of both laws.
If Christians hope to regain an influence in the moral, legal, and ethical debates of the day, we need to be able to develop and present a uniform and compelling case for biblical principles that can persuade skeptics and non-believers alike. The Church can regain an articulate, reasoned, and ultimately influential voice in the public square by rediscovering a strong natural law tradition. Budziszewski argues that natural law allows a Christian to “get somewhere by proclaiming extrabiblical truths which we know, on biblical authority, that the nonbeliever really knows too.” This should bring confidence to Christians as they attempt to effectively engage a post-Christian nation on matters of how we ought to order our lives together.
 Wesley, John. Explanatory Notes, 464.
 All references of Scripture are from the English Standard Version (ESV).
 Amos 2:11.
 Amos 1:6-13. Some may object that the Old Testament depicts Israel doing similar unjust actions without punishment, but it is important to note that natural law is not being disobeyed. Much of the confusion lies in the fact that many of the standard interpretations of Old Testament presented by critics of the Christian faith fail to understand the surrounding textual and historical context of those actions (for more see: Copan, Paul. Is God a Moral Monster? Making Sense of the Old Testament God Grand Rapids, MI: Baker Books, 2011.)
 Girgis, Sherif. “Reason and Revelation: Why Christians Need Philosophy.” Public Discourse. February 04, 2014.
 J. Budziszewski,What We Can’t Not Know: A Guide (Dallas, TX: Spence Pub., 2003), 25.
 Ibid. 34.
 Ibid. 35.
 SeeJ. Matthew Sleeth, 24/6: A Prescription for a Healthier, Happier Life (Carol Stream: Tyndale House Publishers, 2012).
 Budziszewski,Written on the Heart, 184.
Budziszewski, J. What We Can’t Not Know: A Guide. Dallas, TX: Spence Pub., 2003.
Budziszewski, J. Written on the Heart: The Case for Natural Law. Downers Grove, IL: InterVarsity Press, 1997.
Copan, Paul. Is God a Moral Monster? Making Sense of the Old Testament God Grand Rapids, MI: Baker Books, 2011.
Girgis, Sherif. “Reason and Revelation: Why Christians Need Philosophy.” Public Discourse. February 04, 2014.
Sleeth, J. Matthew. 24/6: A Prescription for a Healthier, Happier Life. Carol Stream, IL: Tyndale House Publishers, 2012.
Wesley, John. Explanatory Notes upon the New Testament. New-York: J. Soule and T. Mason for the Methodist Episcopal Church in the United States, 1818.