Believers themselves, sadly, sometimes transgress fixed moral boundaries. Abraham and Isaac tried the wife-sister stunt three times and were rightly rebuked by pagans on each occasion (Gen. 12:18; 20:9; 26:9–10). In response to cultural decline, Christians can be self-righteously quick to denounce others for moral degeneracy. But we are often the ones who do terrible things, and we shouldn’t think that unbelievers don’t notice.

Get a group of conservative Christians together and before long someone will probably express shock at the latest evidence of cultural decline: “Can you believe what they did?” It’s not nearly as common in such settings for someone to say, “Well, of course outrageous things happen in society — we’re all a bunch of rotten sinners.”

From a biblical perspective, perhaps what is really surprising is not how morally corrupt things can be but how well they often turn out. Many societies have legal, economic, and healthcare systems that, however imperfect, provide tremendous benefits for large numbers of people. Given the moral state of humanity — “every intention of the thoughts of his heart was only evil continually” (Gen. 6:5) — this is remarkable.

Christians have appealed to several theological concepts to explain the existence of these wholesome aspects of human culture. By His providence God works out good results from wicked human intentions. God’s common grace restrains the full outbreak of evil and showers many non-saving blessings upon human life. And many Christian theologians have pointed to natural law to explain the moral instincts and insights of so many non-Christians. Natural law is simply an aspect of natural revelation. God reveals Himself and His moral law in the structure of the created order, including human nature itself as it reflects the image of God. Natural law does not reveal the gospel and has no power to regenerate fallen human hearts. Though natural law does not save, it does press God’s moral claims upon the conscience of all people, even those unaware of God’s revelation in Scripture.

The New Testament refers to Christians as “sojourners and exiles” in this world (1 Peter 1:1, 17; 2:11). By God’s grace in Christ we are already citizens of heaven (Phil. 3:20), but we live temporarily away from home, “in the midst of a crooked and twisted generation” (Phil. 2:15). Natural law must surely play an important role as we seek to live “peaceably with all” (Rom. 12:18) in such a world.

Though Scripture never uses the term “natural law,” it refers to the concept of natural law on all sorts of occasions. Some of the most interesting and relevant occur in the stories about the patriarchs in Genesis. When the New Testament calls us “sojourners,” it points us back to the experience of the patriarchs, the original “sojourners” (Gen. 12:10; 15:13; 20:1; 21:34; 23:4). The patriarchs were believers in the true God, living amidst pagans and without a true home in this world. Scripture wishes us to learn something about our life in the present world by observing the patriarchs in their world. How did the reality of natural law shape their sojourn?

The fascinating encounter between Abraham and the pagan king Abimelech in Genesis 20 is an illuminating example. Fearing for his own life when he entered Gerar, Abraham announced that his wife Sarah was his sister, and Abimelech promptly took Sarah for himself. Informed by God that Sarah was Abraham’s wife, Abimelech confronts Abraham: “What have you done to us?” (v. 9). The pagan king is apparently shocked by this reckless disregard for marriage. He accuses Abraham: “You have done to me things that ought not to be done” (v. 9). Abraham replies, “I did it because I thought, There is no fear of God at all in this place” (v. 11). As it turns out, Abraham was wrong. These pagans actually did fear God (in some sense) and understood that people should not do certain things to one another. Natural law had impressed fundamental moral truths upon their consciences.

There are certainly things to learn from this story that are relevant for Christian sojourners today. First, natural law gives unbelievers a sense of moral boundaries that people simply should not cross. Even pagans like Abimelech are sometimes appalled when such boundaries are transgressed. This should provide encouragement and remind us that it is possible to have meaningful moral conversations with unbelievers.

Second, people often transgress these moral boundaries, though they know better, and this can bring great hardship for believers. Jacob’s daughter Dinah was raped by a pagan prince, though “such a thing must not be done” (Gen. 34:7). Sodom and Gomorrah grossly violated social propriety and Lot was forced to flee (Gen. 19). Natural law will never usher in utopia. We should be sober-minded with respect to this world and remember to set our hearts upon the city that is to come (Heb. 13:14).

Third, believers themselves, sadly, sometimes transgress fixed moral boundaries. Abraham and Isaac tried the wife-sister stunt three times and were rightly rebuked by pagans on each occasion (Gen. 12:18; 20:9; 26:9–10). In response to cultural decline, Christians can be self-righteously quick to denounce others for moral degeneracy. But we are often the ones who do terrible things, and we shouldn’t think that unbelievers don’t notice. Christian sojourners should live with circumspection and humility. We must always remember that our own true righteousness is not of ourselves but is a gift of Christ to which we cling by faith.

David VanDrunen is a minister in the OPC.  He hold degrees from Calvin College (BA), Westminster Seminary California (MDiv), Trinity Evangelical Divinity School (ThM), Northwestern University School of Law (JD) and Loyola University Chicago (PhD).  He is the Robert B. Strimple Professor of Systematic Theology and Christian Ethics at WSC.  This article first appeared at the Ligonier Ministries blog, and is used with permission.

@2012 Ligonier Ministries