Jesus was trying to get the Pharisees to come off of their proud, high tower and see the spiritual bankruptcy in their own lives. The Pharisees had no regard for spirituality of soul, purity of heart, integrity of behavior, or obedience to God, and they were building their big spiritual structure on sand. Sure, they prayed and fasted and gave alms, but they did so only to impress God, to parade their supposed spirituality, and to enhance their reputations. They had a religion of externals; that is a religion of sand.