The Insider and the Outcast, Tim Keller

Religious people constantly talk about trusting in God — but if you think your goodness is earning your salvation, then you are actually being your own Savior. You are trusting in yourself. And while you may in this case not be committing adultery or literally robbing people, your heart will increasingly be filled with such pride, self-righteousness, insecurity, envy, and spite that you make the world a miserable place to live for those around you.

– Tim Keller