The greatest enemy of faith is not doubt; the greatest enemy of faith is fear. Most of the world is controlled by fear, petty and big. Petty fears control people; great fears control nations. We could feed all the people in this world if we would stop building arms, but we are afraid. In the Beatitudes (Sermon on the Mount) Jesus said, "Those of you who make peace will he happy. You will be God's own." Yet even Christians are preoccupied with fear and protecting ourselves because we don't believe what Jesus said. The Sermon on the Mount is an antidote to fear. But we have never seen fear as the crucial issue, only "doubt."
Radical Grace, p. 349, by Richard Rohr