The Gospel according to Mark summarizes the theme of Jesus’s preaching at the beginning of His ministry as follows: “The time is fulfilled, and the kingdom of God has come near; repent, and believe the good news” (Mark 1:15).
It is well-known that the verb “repent” (metanoeite) means: “change your way of thinking.” And it is significant that Jesus’s preaching appeals to this. He says that the kingdom of God has come near, but He also says that the people around Him must change their way of thinking. It is therefore not enough for the kingdom to draw near to people. These people must also change their way of thinking in order to be able to participate in the arrival of this kingdom.
Jesus is demanding that we think that things can be better than they are now. This is why He says: “Believe the good news.” Good news means that things are or at least can be better than one might have thought otherwise. The good news He preaches includes believing that our sins are forgiven, that we are the children of God, that we can be healed of sickness, that we can receive the things we ask for, that God will work justice in the world, and so on. But we must also change our way of thinking and believe in these things.
What good is it for God to forgive us of our sins, if we don’t believe that we are forgiven? Then we wouldn’t know that we have peace with God, we would run away from Him, and we would ruin ourselves, whether because we are convinced He hates us or else because we don’t even know that we have done anything wrong. Or what good is it for God to consider us His children, if we do not live as though He were our Father? Then we would still live in the lifeless dread and anxiety of thinking that we are orphans in the world. We must change our way of thinking in order to benefit from these realities.
Part of being a Christian means believing the good news that Jesus brings. It means believing that things can be better than we might otherwise have thought, indeed better than they are now.