C.S. Lewis talked about a God shaped hole in our hearts that only God can fill. I would also suggest we have an ethics shaped hole in our hearts that only God’s perfect justice can fill.
Immanuel Kant wrote the Critique of Practical Reason and in this he outlined three things required to make ethics meaningful. The first requirement was justice. Obviously, if crime ‘paid’ then any reason to do what is right, or honorable, would be meaningless. The second requirement would be perfect justice and since, in this world that is impossible, Kant reasoned that it must take place somewhere else. Finally, the third requirement would be a morally perfect judge, which we as Christians call God.
R.C. Sproul wrote Defending Your Faith an Introduction to Apologetics, and in this book he talked about the Moral Law. “…we see in Kant’s argument that in order to have ethical standards, there must be perfect justice; and in order to have perfect justice, a perfect judge must exist – one who is above reproach and beyond corruption. But what must this judge have in order to be morally perfect and make perfect judgments? The answer Kant offered was ‘omniscience’.” In other words, a God who is all knowing, all loving, and all powerful.
In I Don’t Have Enough Faith To Be An Atheist, Norman Geisler and Frank Turek outlined the Moral Law as follows:
Every law has a law giver.
There is a Moral Law.
Therefore, there is a Moral Law Giver
Everyone, whether they admit it or not, has a basic knowledge of right and wrong. Even people who have murdered others will admit it was wrong, even though some may not have any regret, or feel any remorse for what they have done. It does not matter where you live, how you were raised, we all have an innate sense that murdering other human beings is wrong. Where did this sense come from? In every culture, in every civilization, this understanding has been universal, that the murder of others without cause is morally perverse. Geisler and Turek went on to explain that it is not our actions that determine if we have a moral law, but our reactions. History is full of events of human suffering and mistreatment toward one another that have cost thousands, or millions, of lives, but what makes the moral law so visible, so obvious, so unmistakeable is our reactions to these events. Someone may say they don’t believe in a moral law, but do something to them personally, which they strongly disagree with and you will see a reaction that suggests a moral law. When someone has their iphone or ipad stolen, dog or cat poisoned, family member attacked or murdered, their reaction will suggest they have a moral standard that was crossed and violated. C. S. Lewis said, “My argument against God was that the universe seemed so cruel and unjust. But how had I got this idea of just and unjust? A man does not call a line crooked unless he has some idea of a straight line. What was I comparing this universe with when I called it unjust?”
Proverbs 21:2 A person may think their own ways are right, but the Lord weighs the heart.