Responding to Matthew Anderson’s new CT article, Joe Knippenberg kicked off an interesting conversation on evangelicals and natural law. If you want to see a fair test case of evangelicals and Catholics working to figure out how to talk to each other about this, check out the comment thread.
Natural law is just a subtopic of the larger problem of mapping out the borders and the interaction between the church and the world. What this always comes down to is the need to balance the two different ways in which the Bible characterizes God’s revelation of himself to the human race at large. These are neatly summarized in Romans 1 (to which Mohler appeals) and Romans 2 (the touchstone text for defending natural law).
In Romans 2 we get God equipping all human beings with a conscience that enables them to discern right from wrong - and that continues to impact their behavior (though not in a saving way) even after the Fall. Barth denied that last part, but all the original reformers affirmed it, and it was affirmed consistently within the Protestant theological tradition until Barth and others expelled it in the 20th century . But natural law has been slowly but surely returning in evangelical thinking (although it’s not always called “natural law”). Mohler affirms the intrinsic (note that qualifier - it’s going to be important) validity of natural law because he knows, from Romans 2, that the natural man has this natural revelation.
However, in Romans 1 we get something very different. We get, not a conscience that tells us right from wrong, but a personal, holy creator God revealed in wrath against sin. We then get a human race that suppresses this revelation, and a God who “gives them up” to evil desires. Perhaps most importantly, what we get is not just sin, but a social system in which sin is justified and approved. “Though they know Gods decree that those who practice such things deserve to die, they not only do them but give approval to those who practice them .” (v. 32)
Hence the intrinsic validity of natural law arguments must be integrated with an acknowledgement that the world maintains a social system of approval for sin. The natural man is at war with himself, and natural society is at war with itself. It finds that it cannot avoid - and it usually does not want to avoid - some role for the Romans 2 revelation. But that role must be kept carefully in check, lest it lead us to an encounter with the Romans 1 revelation, the wrathful God whose unbearable holiness cannot at any cost be permitted to penetrate our awareness.
Hence the perpetual controversy over the motto “In God We Trust” - those who back it do so because it’s an attempt to walk people from the Romans 2 revelation to the Romans 1 revelation. Those who opppose it do so for exactly the same reason. (Whether the attempt is well advised or ill advised from a prudential standpoint is a separate issue that we don’t need to get into here.)
And the particular challenge for evangelicals is that our theology implies that the social system of approval for sin, while it cannot eradicate the witness of the conscience, will always maintain the dominant position over its influence - except insofar as the Holy Spirit regenerates people, and those people in turn have an impact on the social system, if only by their presence within it.
This last part is not a necessary position in Roman theology, and while some adherents of the Roman school have held it, it is definitely not predominant. The predominant mode in the Roman tradition is to say that the war can go either way, even independent of the church’s influence.
In particular, I suspect (with a willingness to accept correction) Joe doesn’t have Thomas Aquinas quite right:
Certainly St. Thomas Aquinas wouldnt rely simply on rational argumentation, but recognizes also at least the compulsory and edifying aspects of human law. In other words, argument always occurs in a cultural and social context, a context that Thomas surely recognizes must be affected by human sin.
Verily, Aquinas does recognize that sin affects the social system. But I don’t think (again, under correction) that Aquinas shares the evangelical view that the influence of sin must always have the upper hand over the influence of conscience except where the Holy Spirit and the presence of Christians in the culture empowers the conscience.
This is why the issue of how the church impacts the world is so important, yet so difficult, for evangelicals. For a century we seem to have been oscillating between isolationism and uncritical assimilation of the world’s sin-rigged agendas. We need to figure out another way to go. Natural law is not the whole picture - but a recovery of our four-century natural law tradition (call it something else if the phrase “natural law” bothers you) has to be part of it.