Jung said “You are what you do, not what you say you’ll do.” Jesus goes further: Why you do what you do is important. Doing things to impress others instead of doing them because you believe in them does not make you good.
Do not give charitably before other men, to be seen by them, or you will have no reward from heaven. When you give to charity, do not sound a trumpet before you, as the hypocrites do in the synagogues and in the streets, so that they may be praised by men. They will have no other reward. When you give, don’t let your left hand know what your right hand is doing: give in secret, and heaven will reward you openly.
When you pray, do not do as the hypocrites do, for they love to pray standing in the synagogues and in the corners of the streets, to be seen and praised by other men. Their prayers will have no other reward. When you pray, do so in private, and heaven shall reward you publicly.
Moreover when you fast, do not, as the hypocrites do, look sad and disfigure your face, to make it apparent to others that you fast. When you fast, remain clean and tidy, so that you don’t appear to be fasting, and heaven will reward you openly.
He summed it up best in his criticism of the Pharisees, a Jewish sect known for priding themselves in strictly following the law of Moses and holding themselves superior to others:
You Pharisees clean the outside of the cup, but inside you are full of greed and wickedness.