What strikes me as being significant about todays Gospel, is the fact the Pharisees go away. They are praiseworthy in so far as they recongnise they too are sinners, when Jesus says, "Let he who is without sin cast the first stone."
If we think of ourselves as being sinless we have no part in Christ. He came for sinners, not the just. He came as the physician for the sick, not the well.
In order to be part of Chirst we have to own our sin.