Comment: I don't know if the bishops ever told priests that if they rape a child and celebrate Mass they are committing sacrilege.  But even if they didn't, the priest should know that...it is pretty basic Catholicism that receiving Communion with a mortal sin on your soul is sacrilege. 

By the logic of your second paragraph, there can never be a mortally sinful sexual act, since sex acts by definition occur in a state of passion.  Which begs the question, why in this case would the Scriptures go through the trouble of condemning sexual immorality? This sounds like something your example of a rapist priest could say to himself to justify himself taking Communion in a state of mortal sin.