'...and be kind to one another, tender-hearted, forgiving one another, as God in Christ has forgiven you. Therefore be imitators of God, as beloved children, and live in love, as Christ loved us and gave himself up for us, a fragrant offering and sacrifice to God.' (Ephesians 4:32 - 5:2)
In the Lord's Prayer, the only thing that is asked of us, is that we forgive those who do us wrong, in exchange for that our Father in Heaven forgives us our wrongdoing. Here, in this passage from Paul's letter to the Christians in Ephesus, we see why. God has forgiven us in Christ. In that, he has set us a pattern, a way of conducting ourselves that we can imitate. When we grow up, we often look towards those who are older, or wiser to show us the way. We want to be like them. As God is our Father, we should strive to be like him. But more than that, we should strive towards imitating Jesus Christ, our older brother, whose self giving love was poured out for us.