In Luke 18, Jesus tells a parable to a group of people who "trusted in themselves that they were righteous" and in speaking to them, He also speaks powerfully to us. The contrast between the religious, self-reliance of the Pharisee and the Tax Collector underscore how God looks at the heart, not just our actions. Those who are sinners, and know they are sinners, find mercy and grace when the come to God in humility.