This is why God sent John – to give his people this kind of fear, the kind that prompts the question, “what then should we do?” God continues to send fire and brimstone preachers for the same reason – because if you haven't been reminded about the wrath to come, you might forget that you need a saviour to change you.
And ultimately, God sends his son Jesus, who baptizes us with fire and the Holy Spirit, so that we are ready to receive him. It's the Holy Spirit within us who guides us constantly to fear the consequences of sin. And this fear enables us to grasp and hold what Jesus brings for us through his sacrifice on the cross – God's forgiveness. Think about it – if you have been rude to someone like say a store clerk or a waitress in the city, how motivated are you to go back and seek forgiveness? You will likely never see this person again, and they have no influence over you – there are zero consequences. Chances are, you won't make a trip back to the city just to apologize. But if you have been rude to your employer or your commanding officer or even your children, the consequences could be severe, and so you will actively seek forgiveness. The wrath to come are the consequences that prepare us to cling to the forgiveness that Jesus promises.
And it is that forgiveness that gives us the impulse to truly repent. It is the undeserved forgiveness of God that changes our hearts. It is the undeserved forgiveness that enables us to follow Jesus and become his disciple. And as Jesus changes us, we go from being chaff to being wheat. We become people of justice and mercy, and our fruits of repentance become visible. It all stems from God's forgiveness, which Jesus made possible for us through his sacrifice on the cross.
There are some people who have a problem with a God who shows wrath. But the sacrifice of Jesus shows us that God's wrath is not what they think, the wrath of a tyrant or a slave-driver. Instead, God's wrath is that of a loving parent, who's teenager has just crashed the family car with reckless driving. Sure, God's upset that other people were hurt. Sure, God's upset that the car was totalled. But at the root of God's wrath is this, “You could've gotten yourself killed.” At the root of wrath, is a love deeper than we can possibly comprehend.
Gracious God, we cling to your son Jesus, who saves us from your wrath by changing us as his disciples. Help us to always fear the consequences of sin, and to feel your love behind the wrath, in Jesus' name, amen.