"You have heard that it was said to the men of old, 'You shall not kill; and whoever kills shall be liable to judgment.' But I say to you that every one who is angry with his brother shall be liable to judgment; whoever insults his brother shall be liable to the council, and whoever says, 'You fool!' shall be liable to the hell of fire. So if you are offering your gift at the altar, and there remember that your brother has something against you, leave your gift there before the altar and go; first be reconciled to your brother, and then come and offer your gift. Matthew 5:21–24 (RSV)
Jesus is always asking more of us than we can imagine we can do. True, we are saved by grace through faith in Jesus Christ, but Jesus leads us to live a new life. We are to live a life of repentance and reconciliation. We are to be signs of the Kingdom at work in the world.
Repentance is being honest about ourselves before God. We are sinners. We sin by thought, word, and deed, by what we have done and left undone. We confess our sin to God. We are also to confess our sin to those whom we have sinned against.
Confession and repentance are not intended to be easy. We don't just get to say, 'I'm sorry,' and it's all good. Repentance recognizes the damage done by our sin. A Christian who has repented seeks to be reconciled to God and those we have sinned against. Repentance is a challenge. Reconciliation is the hard work that follows repentance. We seek to undo the harm done by our sin. Reconciliation means person to person encounter when we begin to undo what was done. It may be that all that is needed is an apology. It may take more. We may need to restore what was lost or damaged. It may take a radical change in our life, becoming a more mature Christian.
This will be our life in Christ. As Luther writes, the Christian life is one of repentance (and reconciliation)