Knowing who the sinner is
But much more happens than just an emotional foot washing. There is also this reaction:
When the Pharisee who had invited him saw this he said to himself, “If this man were a prophet, he would know who and what sort of woman this is who is touching him, that she is a sinner.”
The Pharisee thinks that Christ should read minds and hearts. What he fails to realize is that Christ reads the Pharisee's mind and heart as well.
The Pharisee thinks Christ should know that the woman is a sinner. What he fails to recognize is that Christ not only knows that, he also knows the sin in the Pharisee’s own heart.
We ourselves need to be clear about sin, generally and concretely: in the world around us, but most especially in our own hearts.
We ourselves need to welcome the Lord Jesus into our dark and narrow hearts, so that he may open us fully by his grace to the fullness of his truth and his love and that we may overcome sin with the power of his forgiveness.