In those days John the Baptist came, preaching in the wilderness of Judea 2 and saying, “Repent, for the kingdom of heaven has come near.” (Matthew 3:1-2)
From that time on Jesus began to preach, “Repent, for the kingdom of heaven has come near.” (Matthew 4:17)
John actually started preaching Jesus’ message before Jesus did – repent because the kingdom has come.
The kingdom and repentance are linked. Why?
The kingdom of God (or “of heaven” in Matthew) is life when God is in charge; it is life when everything is in line with God’s will.
When we are unaware of the kingdom we live in ways inconsistent with it. We think anti-kingdom thoughts and do anti-kingdo deeds without even being aware of it. But when the kingdom breaks in on us we must change. That is what Jesus proclaimed.
The very next chapter Jesus begins to describe the outlines of the kingdom in what we call “The Sermon on the Mount”. It is full of counter-intuitive challenges about how to live, like love your enemy, turn the other cheek, etc. On our own, we wouldn’t naturally think of doing these things. They aren’t “natural”, they are supernatural; they are expressions of the kingdom. Jesus is announcing and demonstrating these kingdom ways, and calling us to repent. (which means to change our thinking/mind). In order to experience the kingdom it is not just that we need to ask forgiveness for our sins, which we do because they are anti-kingdom ways. We also need to let God give us a brand new way of looking at the world and what is the right way to live. Repent because the kingdom has come near.