As part of my sabbatical here in Cambridge, England, I am working on a book with the tentative title What Jesus Demands From the World. The demand to repent is as basic as it gets in Jesus’ message. It is equally basic to, and almost synonymous with, the command, “You must be born again” (John 3:7). One of my concerns is to show that repentance in Jesus’ message is not behavior but the inner change that gives rise to new God-centered, Christ-exalting behavior. Here are some thoughts to help make the meaning of repentance more plain.

From that time Jesus began to preach, saying,
“Repent, for the kingdom of heaven is at hand.” (Matthew 4:17)

I have not come to call the righteous but sinners to repentance. (Luke 5:32)

The men of Nineveh will rise up at the judgment with this generation and condemn it,
for they repented at the preaching of Jonah,
 and behold, something greater than Jonah is here. (Matthew 12:41)

Unless you repent, you will all likewise perish. (Luke 13:3, 5)

The first demand of Jesus’ public ministry was, “Repent.” He spoke this command indiscriminately to all who would listen. It was a call for radical inward change toward God and man.

Two things show us that repentance is an internal change of mind and heart rather than mere sorrow for sin or mere improvement of behavior. First, the meaning of the Greek word behind the English “repent” (metanoeo) points in this direction. It has two parts: meta and noeo. The second part (noeo) refers to the mind and its thoughts and perceptions and dispositions and purposes. The first part (meta) is a prefix that regularly means movement or change.  So the basic meaning of repent is to experience a change of the mind’s perceptions and dispositions and purposes.

The other factor that points to this meaning of repent is the way Luke 3:8 describes the relationship between repentance and new behavior. It says, “Bear fruits in keeping with repentance.” Then it gives examples of the fruits: “Whoever has two tunics is to share with him who has none, and whoever has food is to do likewise” (Luke 3:11). This means that repenting is what happens inside of us that leads to the fruits of new behavior. Repentance is not the new deeds, but the inward change that bears the fruit of new deeds. Jesus is demanding that we experience this inward change.

Why? His answer is that we are sinners. “I have not come to call the righteous but sinners to repentance” (Luke 5:32). What was Jesus’ view of sin? In the parable of the prodigal son, Jesus describes the son’s sin like this: “He squandered his property in reckless living . . . [and] devoured [it] with prostitutes” (Luke 15:13, 30). But when the prodigal repents he says, “Father, I have sinned against heaven and before you. I am no longer worthy to be called your son.” Therefore, throwing your life away on reckless living and prostitutes is not just humanly hurtful; it is an offense against heaven—that is, against God. That’s the essential nature of sin. It’s an assault on God.

We see this again in the way Jesus taught his disciples to pray. He said that they should pray, “Forgive us our sins, for we ourselves forgive everyone who is indebted to us” (Luke 11:4). In other words, sins that God forgives are compared to the ones people commit against us, and those are called debts. Therefore, Jesus’ view of sin was that it dishonored God and put us in debt to restore the divine honor we had defamed by our God-belittling behavior or attitudes. That debt is paid by Jesus himself. “The Son of man came . . . to give his life a ransom for many” (Mark 10:45). But for us to enjoy that gift he says we must repent.

Repenting means experiencing a change of mind that now sees God as true and beautiful and worthy of all our praise and all our obedience. This change of mind also embraces Jesus in the same way. We know this because Jesus said, “If God were your Father, you would love me, for I came from God.” Seeing God with a new mind includes seeing Jesus with a new mind.