Most of us know that repentance is an indispensable part of the Christian life and that it goes with saving faith as two sides of the same coin. But I am not so sure how many of us know what repentance should look like in practice. Some of us may well think of repentance behaviorally and believe that it means only saying that we are sorry or making a change in the way that we are living our lives. Others of us may think of repentance attitudinally, as though it means only being disappointed in ourselves or feeling sorry for what we have done. But, while all of these things may be a part of what it means to repent, none of them captures the essence of what repentance actually is. Genuine repentance is more than a change in behavior or feelings; it is fundamentally a change in heart.

We see this, for instance, in Matthew 3:8, where John the Baptist warns the Pharisees and Sadducees that they need to “bear fruit in keeping with repentance.” This tells us at least two important things about genuine repentance. First, repentance is fundamentally something that happens on the inside of a person. John Calvin called it “an inward matter, which has its seat in the heart and soul.” It is not, therefore, primarily about our outward behavior but about our heart’s desires. That is why the prophet Joel pleads with the people of Judah to “return” to the Lord “with all [their] heart” and encourages them to “rend [their] hearts and not [their] garments” (Joel 2:12–13). He is indicating that repentance is essentially a heart matter. But it is a heart matter that leads to an outward change in behavior. And that is the second thing that John the Baptist’s warning emphasizes. The inward change of repentance should lead to an outward change in the way we are living our lives. The outward change is important, but only as the necessary consequence of genuine repentance on the inside.

This emphasis on repentance as a heart matter is exactly what we should expect, given that the Bible repeatedly speaks about faith—the flip side of repentance—in terms of the heart. Thus, Paul says that everyone must “confess with your mouth that Jesus is Lord and believe in your heart that God raised him from the dead” in order to be saved (Rom. 10:9; emphasis added). And we see that Peter warned Simon the Magician that his “heart is not right before God” after he had tried to buy the power of the Holy Spirit with money, thereby demonstrating that he had never truly believed in the first place (Acts 8:13, 19–22). Because faith and repentance go together, and because faith is a matter of the heart, we know that the same thing applies to repentance as well. Thomas Watson expressed it this way: because the heart is “the first thing that lives,” it must also be “the first thing that turns.”

But what does it mean to repent from the heart? John Calvin once famously described the human heart as an “idol factory” that is continually manufacturing new gods to serve. In speaking this way, Calvin acknowledged that the business of the Christian life is primarily carried out at the level of the heart. Jesus wants all of our heart, soul, mind, and strength (Mark 12:30). He doesn’t want only outward obedience. He wants obedience that comes from a heart that delights in Him and that recognizes that the “steadfast love” of the Lord really “is better than life” (Ps. 63:3). Despite this, because of sin, our hearts are prone to wander, prone to leave the God we love. To borrow Calvin’s illustration, our hearts are idol factories that are constantly rolling out substitute gods one after another on an assembly line.

The Christian life is fundamentally about destroying the idols that our hearts are constantly producing.

But these “factories” don’t produce their goods ex nihilo—out of nothing. Rather, they take the good gifts that God has already provided to us and pervert them by assigning them a place of preeminence in our lives. As C.S. Lewis says, our hearts take second things and put them first. We take good gifts such as work, family, money, accomplishment, sex, food, and drink, and we make them ultimate things in our lives. We give our hearts to them, and we serve them with our thoughts, our time, our priorities, and our resources. We allow these things to become substitutes for God. Because of the sin that remains in us, this is what we are “prone” to do. In the words of the hymn writer, our hearts are prone to wander. In the words of Calvin, they are idol factories.

This means that the Christian life will necessarily be a constant struggle to recognize these new idols of the heart and then to tear them down. Or, using Lewis’ categories, we recognize that second things have in fact become first things, and then we seek to remove those second things from their place of preeminence and restore them to their rightful position. This is what genuine repentance is all about: tearing down the idols of our hearts, destroying them completely. We do that when we take our hearts away from the idols that have possessed them, and we give our hearts back to God.

This has been one of the most helpful realizations in my own Christian life over the last five or six years. For a long time, I looked at repentance in almost exclusively behavioral terms. I saw it as a 180-degree change in my outward actions. But, all the while, I gave little attention to the desires of my heart. More recently, I have come to see that genuine repentance must focus on the heart. It must begin with changing my heart’s desires. I must take my affections away from whatever substitute gods I have been serving and fix them again on Christ. I must tear down every new idol of my heart, destroying it completely, and give my heart to Christ again “promptly and sincerely,” as Calvin said so long ago. This is a daily struggle. It is the daily struggle of the Christian life.

I once heard Dr. R.C. Sproul summarize Calvin’s idol-factory language by referring to the human species as Homo faciens—which means “man, the maker”—rather than the scientific label Homo sapiens—which means “man, the wise or discerning.” His point was that the human species ought to be classified scientifically by that which chiefly characterizes it. And “idol makers” does that much more accurately than “wise men.” If we apply R.C.’s logic to what we have said about repentance in this article, we can rightly conclude that Christians ought also to be called Homo destruens—which means “man, the destroyer”—because the Christian life is fundamentally about destroying the idols that our hearts are constantly producing. In other words, it is precisely because you and I are Homo faciens that we must also be Homo destruens. Then and only then will we begin to see real victory over sin in our lives, and then and only then will we experience real and lasting joy in Christ.

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