Playing Offense: How Christian Natural Law Arguments Work in Public Apologetics

Published April 21, 2022

Southern Seminary Magazine

For many Christians in our culture, it’s easier to stay silent when one is in the minority opinion about a controversial topic rather than risk disturbing the status quo. Of course, there are wisdom issues about knowing when to speak up, and not everyone is called to join the battle in all the same ways. 

But being in the minority does not excuse a total refusal to speak up—especially when Christians have better answers to the most pressing challenges of our day that threaten to tear apart our social order and rob individuals of the flourishing they are owed as image bearers. And that’s the whole point I want to argue: Christians have better, more satisfying answers to explain the confusion and conflict that plagues our contemporary culture, so we should speak up. To engage in public apologetics, though, Christians must understand the types of arguments we need to make.

Making Sound Arguments

Much of my role as an ethics professor at Southern Seminary is convincing students that on the most controversial issues of our day, the best answers are not only Christian answers, but Christian answers are also the most coherent answers one could offer to their secular neighbor. To do public apologetics—to make arguments in hopes of explaining and persuading—requires us as Christians to understand the relationship between faith and reason. We must understand the reasonableness of the ethics we hold as Christians if we hope to make arguments that would hope to see individuals converted and culture more humane.

I’ll use a famous illustration to explain my point. In his Letter from a Birmingham Jail, Martin Luther King, Jr. made a profound argument for overturning racist laws. But it was not just the conclusion he reached that we should agree with; it was how he got there, too. His argument, which was intended to be publicly accessible and persuasive for pricking consciences and changing laws, appealed to the Christian natural law tradition. Citing Augustine and Thomas Aquinas, King argued that “an unjust law is not law at all.” He wrote: 

 “How does one determine whether a law is just or unjust? A just law is a manmade code that squares with the moral law or the law of God. An unjust law is a code that is out of harmony with the moral law. To put it in the terms of St. Thomas Aquinas: An unjust law is a human law that is not rooted in eternal law and natural law. Any law that uplifts human personality is just. Any law that degrades human personality is unjust. All segregation statutes are unjust because segregation distorts the soul and damages the personality.”

What King meant was that a law that purposefully harms does not retain the actual power to command obedience; it is thus not true law. Justice can never entail the denial of what is owed to persons. That is, well, unjust. A law, after all, is a standard or measurement that obligates individuals to obey its precepts on the basis that the precept advances some rational good. All truly sound laws will reflect an ordinance of reason that directs persons to their good. To say a law is reasonable means it accomplishes justice. But a law that obstructs or thwarts the good cannot be an actual law because it is unjust. King argues that not only are racial supremacy laws in violation of Christian theology; they violate all rational grounds for justice as well. A true law reflects the principle of justice. A law that does violence to one’s neighbor is wrong because we can grasp the harm the law perpetrates. We would ourselves not want to be on the receiving end of that unjust law’s application. This explains the logic behind the Golden Rule in Luke 6:31. Jesus assumes that any action is just toward others insofar as it is the type of action we would want applied to ourselves. No one in their right mind goes looking to harm themselves for no good cause, so likewise, any law that harms others cannot obtain the grounds of justice, either. Crucially, it’s worth noticing that King does not pit reason against theology. Instead, he shows us the reciprocal relationship of both. That, I suggest, is what the task of public apologetics requires. We must explain how the theological premise of our conviction can be embraced by, and bears relevance to, the interest of our secular interlocutor.

Widening the Sufficiency of Scripture

King’s argument serves as a model for how Christians should think about the types of arguments we make. Yes, we should make our case from Scripture and see it as our ultimate and all-sufficient authority, but Scripture is not the only tool in our arsenal that God gave to us, and we would be wrong to assume that knowledge of right and wrong are disclosed only in Scripture. This in no way violates our understanding of the Bible’s sufficiency but widens it. 

A narrow sufficiency that does ethics only by proof-text alone will, unintentionally, leave Christians without answers to a whole host of questions. A broader sufficiency, one that encompasses how Scripture speaks over all of created reality, broadens our understanding of the Bible’s relevancy to public apologetics.

The task of public apologetics will often require us to go beyond the pages of Scripture, but never against it. God is the source of all moral knowledge, but a God-implanted moral knowledge is broader than what is contained in Scripture. True moral knowledge resides in all persons regardless of their acknowledging God. He gives humanity the powers of reason and cognition to know whether something is true or false on its own grounds (Rom. 2:14-15). We may suppress the truth or err in our application of the moral law (Rom. 1:18-21), but Scripture attests to the reality of the moral law. Nowhere does Scripture argue that non-Christians are incapable of knowing truth. Scripture argues that non-Christians suppress the truth. 

The world the Lord creates is known to us by a divinely endowed capacity for reason. To say that image bearers can know by reasoning is to insist that the Lord does not make the splendor of this world unintelligible. Sin mars our reason, but it does not render us blind to the knowledge of a creation that “proclaims his handiwork” or deaf to a world that “pours out speech” (Psalm 19:1-3).

What does this have to do with public apologetics? It means we’re going to have to engage in reasoned debate about deeply moral questions. All moral law certainly emanates from God, but that does not mean one who does not believe in God does not have actual moral knowledge. The unbeliever may have no solid ground upon which to base their morality, but unstable foundations do not invalidate that the knowledge they do have is true. That may sound like I am investing too much weight or optimism in reason itself. That’s not my intention. Instead, I want us to understand that a secular progressive’s refusal to agree with Scripture also signals their refusal to agree with what are ultimately the sound principles of morality as such. Principles of morality will be sound or they will not be, regardless of the non-believer’s understanding of their foundation. A non-believer may want to argue that an apple is an orange or a man can be a woman, but if they insist upon an irrational conclusion, a part of the task of apologetics is not only offering sound foundations but also sound principles for determining the nature of reality and truth as such. We can and should debate origins, but what we should be concerned preeminently with, is truthfulness. If God’s world is one of order, there must be truth to be understood. If that is true, Christians are called to every sphere of engagement for God’s glory.

God speaks with one voice in two ways: In Scripture and in creation. Suppose we pit these two against each other, as though faith and reason are opposites. In that case, we do violence to Scripture and send the wrong signal to unbelievers that they are justified to sever reason from faith, as though there are degrees of knowledge incompatible with faith. 

Now, some aspects of reason may be incomplete, but they are never incompatible with faith. For example, an unbeliever might not know God as triune. Still, the same triune God of Father, Son, and Holy Spirit is also the God who rationally ordered a universe where all can know injustice exists and should be rectified. Creation order speaks (Psalm 19; Rom. 1:19-20). An unbeliever may not be able to give account for the identity of the triune God, but they could, in principle, understand that abortion is wrong. And that’s because the world God created is intelligible. It explains why non-Christians can make wonderful discoveries or become experts in medicine: The world has order to it.

Biblical Morality Is Truly Reasonable

Scripture speaks in a panoramic way when it comes to morality. The whole edifice of Christian morality should cause us to point our interlocutor to God because without God, there can be no stable foundation of morality. We should not let our secular neighbors off the hook because they reject Scripture. We should also ask them: From whence does your understanding of sound ethics derive? Morality reduces to two options: Either (1) A transcendently given morality that is universally true and objectively accords with reason and reality as such, or (2) a contingent, evolving neural mechanism promoting dopamine-like sensations based upon group, preference, and power.

If all moral knowledge is known exclusively by Scripture rather than ultimately by Scripture’s testimony of God’s sovereignty, we might unintentionally forfeit the ground on which we’re called to play, which is everywhere. But neither should we ever grant the premise that the morality Scripture speaks of is anything ever less than truly reasonable. Thus, to jettison Scripture, in other words, is to jettison reason itself because the Lord is a God of reason, not sheer will. God does not create Christian morality “over here” and non-Christian secular morality “over there.” The Triune God is not only the God over salvation but also creation, which means when God rationally orders the universe, the morality that goes with it is not bifurcated between “Christian” and “non-Christian.”

We see this in Genesis 1. 

Genesis describes a creational order that bears witness to creation as such, not simply a Christian view of creation as though the world we inhabit as Christians is different for non-Christians. No, there is one God, one cosmos, one world, and one morality. The beauty of Christian ethics is that properly ordered reason will always harmonize with what Scripture teaches is true. Reason is subordinate to Scripture but never at odds with it. There is no tension and can never truly be. God is not a God of chaos, irrationality, or contradiction.

Our ethics are never less than biblically rooted, but biblically rooted ethics necessarily spin us outward. Our knowledge is not valid insofar as it only agrees with Scripture, but reason as well. But if it’s reasonable, it will never be at odds with Scripture. If there are reasoned justifications for the ethics we espouse that satisfy the criteria for rational soundness, then where that truth is located—whether in special revelation or general revelation—is irrelevant. 

What matters is whether the argument in question is true or false. No tenet of Christian ethics will ever be at odds with what reason can know as true. Therefore, when we speak of “Christian Ethics,” we speak of an inherently public discipline because Christian ethics are grounded in creation, divinely attested to in Scripture, and confirmed by reason. The truthfulness of our ethics is not a private, self-disclosed reality.

Deploy the Full Range of God-Given Arguments

What I want to encourage you with in this brief essay is not so much the correctness of Christian ethics upon such matters as abortion, sexual ethics, and gender—and indeed, they are true—but how Christians should think about our arguments in themselves. I say this because there is a tendency among Christians to think that our viewpoints only have merit because they are found in Scripture. Of course, they have infinite worth because they are found in Scripture, but their soundness expands beyond just Scripture. Their truthfulness reflects the pattern of an orderly creation patterned by God. Practically speaking, it means the pro-choice advocate or transgender activist is revolting against both reason and revelation.

But I’d like to suggest that grounding our ethics and the call to public apologetics in Scripture alone is to bypass the full range of arguments that God gives us. We should never appeal any less to Scripture. We are, after all, Protestants who believe in sola Scriptura. But sola Scriptura is not solo Scriptura. It has never been the position of Christian ethics that authority is found only within Scripture, but that Scripture is our ultimate authority. What questions this raise is whether there are other valid sources of authority that Christians should consider when making public arguments. Sound reason that comports with God’s creation is one of them.

All matters of public policy and cultural flashpoints subject to intense debate in the public arena, if they are essential to organizing our shared life around, ought to and can be debated on the basis of reason, which is never disconnected from theology, but merely its entailment. Further, any principle of public policy that a Christian would want to see codified as a sound reflection of biblical morality would necessarily be grounded in the natural law. Any cultural debate that requires Christians to offer a definitive response must never be at odds with reason; if it were, it would not be grounded in God’s eternal law from the start.

For example, it is either reasonable or unreasonable to kill an unborn child in the womb. This is either a morally good act or a morally evil act. What it cannot be is morally benign. Reasoned arguments that are grounded in a scriptural worldview require us to consider whether the principle that would license abortion is in fact worthy of our affirmation. But both reason and revelation testify to abortion’s unreasonableness. It constitutes the unlawful taking of human life, which is a violation of the right to life and God’s authorship of life, and it is therefore a violation of the sixth commandment (Ex. 20:13). 

But to determine whether abortion violates the sixth commandment, I need to apply principles of reason to determine whether the unborn child meets the threshold of a right to life. That requires understandings of hermeneutics, philosophy, biology, embryology, and ethics. All this means is that in a topic like abortion, we need to argue from all sources that coordinate to the truthfulness of abortion being sinful.

Total Ethics, Total Christ

The task of public apologetics is to bear witness to the total Christ. The Christ who redeems is the same Christ who creates and orders (John 1:3; Col. 1:15-17). Where Christ is rejected, nature and reason are dismissed as well, which produces the very pottage of decay all around us: An anti-culture basking in the absurd and the perverse. 

Perhaps the greatest non-canonical theologian of the church, Augustine, echoed such a similar refrain when he admonished his readers: 

“Let us attend to the real matter in debate, and let our arguments appeal to reason and to the authoritative teaching of the Divine Scriptures, dispassionately and calmly, so far as we are able.”1

There’s no principle of Christian morality, whether decreed in Scripture or attested to in nature, that is not simultaneously ordered to God’s glory and our good. If good, an ordinance of reason; if reasonable, it is sound; if sound, it is binding; if binding, it is God-ordained.

Christianity provides the most consistent, coherent account of morality necessary for the task of public apologetics. It offers God as the source of our ethics, reason as the basis of moral knowledge, and an all-encompassing goal: our good, but chiefly, God’s glory.

1 Augustine, Letter 23 to Maximin.

Photo by Shelagh Murphy on Unsplash

EPPC Fellow Andrew T. Walker, Ph.D., researches and writes about the intersection of Christian ethics, public theology, and the moral principles that support civil society and sound government. A sought-after speaker and cultural commentator, Dr. Walker’s academic research interests and areas of expertise include natural law, human dignity, family stability, social conservatism, and church-state studies. The author or editor of more than ten books, he is passionate about helping Christians understand the moral demands of the gospel and their contributions to human flourishing and the common good. His most recent book, out in May 2021 from Brazos Press, is titled Liberty for All: Defending Everyone’s Religious Freedom in a Secular Age.

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