Charles Williams has said of the Lord's Prayer, "No word in English carries a greater possibility of terror than the little word 'as' in that clause." What makes the 'as' so terrifying? The fact that Jesus plainly links our forgiven-ness by the Father with our forgiving-ness of fellow human beings. Jesus' next remark could not be more explicit: 'If you do not forgive men their sins, your Father will not forgive your sins.'
Philip YanceyAs the books of Job, Jeremiah, and Habakkuk clearly show, God has a high threshold of tolerance for what appropriate to say in a prayer. God can "handle" my unsuppressed rage. I may well find that my vindictive feelings need God's correction - but only by taking those feelings to God will I have the opportunity for correction and healing.
Philip Yancey