"If the church fails to apply the central truth of Christianity to social problems correctly, someone else will do so incorrectly.” Carl F.H. Henry

Why Martin Luther King Matters to Christian Ethics

Today we celebrate Martin Luther King and his significance for racial justice.

As a Christian ethicist, I’m interested in asking what aspects there are of Martin Luther King’s career and approach to activism that are important for Christian ethics today. One of many aspects, and what I want to briefly focus on, is how Martin Luther King demonstrated the importance of a biblically-based view of natural law.

In his famous “Letter from a Birmingham Jail,” Martin Luther King drew upon the work of St. Augustine and Thomas Aquinas for his understanding of what constitutes true legal justice. In his words:

One may well ask: “How can you advocate breaking some laws and obeying others?” The answer lies in the fact that there are two types of laws: just and unjust. I would be the first to advocate obeying just laws. One has not only a legal but a moral responsibility to obey just laws. Conversely, one has a moral responsibility to disobey unjust laws. I would agree with St. Augustine that “an unjust law is no law at all.”

Now, what is the difference between the two? How does one determine whether a law is just or unjust? A just law is a man made 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. It gives the segregator a false sense of superiority and the segregated a false sense of inferiority.

Laws are just, according to King, if they abide by the moral and eternal law of God—not just the law of man. Man can err; God cannot. Man can vote injustice into the law, and indeed did with racialist laws designed to denigrate fellow image-bearers; but God can never be the foundation of injustice.

Moreover, it is important to consider that a modern individual like Martin Luther King drew upon the work of a medievalist in Aquinas and an ancient like Augustine for his conception of justice. Both Aquinas and Augustine had profound insights into natural law, general revelation, and how both shape our understanding of justice being timeless and universal.

But there’s one other reason that King’s approach is so important to Christian ethics. For King, prophetic and biblical witness were never considered opposites of natural law. And that’s how Christian natural law reasoning should be. St. Augustine and Thomas Aquinas were theologians who understood the witness of Scripture to speak truthfully of the eternal and moral law inscribed in human nature. At its best, natural law functions as a pathway for the truth of Christian ethics revealed in the heart, the conscience, and the Scriptures.