“And forgive us our sin” is a direct word-for-word translation from the original Greek, “Kai aphiemi hemin hemon hamartia” (a transliteration). There are no extra words and no excluded words. To appreciate what is being asked of God, I need to understand and accept that I possess sin (hamartia). So, what is sin? What is hamartia (“Chata” in Hebrew.)?
“Hamartia” and “chata” literally mean “to miss the mark”. When these words are used to describe sin, they mean that the person has missed the mark that God has established for the person’s life and being. It does not mean that I discover who I am, sin and all, and accept that this is how I was made and intended to be. I was not made to sin, that is I was not made to miss the mark. Rather, I chose sin. I chose not to live to God’s potential and intent for me. Sin is choosing to miss the mark I can hit. And that mark is good. God’s mark for me is not bad, wrong, or misfortune. God’s mark for me is goodness and good accomplished. All humans except Jesus missed God’s personal mark for them. Therefore, sin is more than violating God’s law.
Sin this like this. I create an item to do something specific and good. My creation is perfectly made to accomplish my intent and that intent is good for the item I created. I give that device the ability to make choices. From the beginning, the item makes choices that keep it from meeting the good intent that it was made for. The choices rotten the device to a point where it is incapable of completing its good and perfect intended purpose. The device missed the mark and in the process destroyed itself.
When I say, “And forgive me my sin” I am asking for absolution and to be made right again.