Forgiveness is always necessary when I have the perception that I failed to love and accept myself or another. Forgiveness allows me to let go of any feelings of inadequacy that arise in me. Forgiving myself is the affirmation that I do not buy into the feelings of inadequacy that invariably arise when I judge myself or another. Forgiveness keeps the slate of my heart open for Spirit to write on.
In terms of faith, it's the story (and not the facts) that grips the imagination, impregnates the heart, and animates the spirit within bringing meaning and integration into one's experience.