As William James noted in The Varieties of Religious Experience, the test of all religious beliefs lies in the lives they produce: “you will know the tree by its fruits.” A comparison of these speeches by Martin Luther King, Jr. and Christopher Hitchens, for example, might lead one to embrace religious belief without further discussion. But for a fine, and entertaining, discussion of the place of faith, engagement, and justice in the world, see Terry Eagleson’s Faith, Reason and Revolution.