Though fashioned as popular entertainment with laughs, light moments, and mostly humorous segments, Maher and the filmmakers are serious in castigating the body of literature whose influence on human history has been overwhelmingly negative. A globe-hopping Maher interviews various representatives of the Western religious faiths of Christianity, Judaism, Islam, and Mormonism. If, as Maher states, 16% of the U.S. population identifies as secular humanists who don't believe in God, then that's a large cross section of the country whose voices are muffled by the status quo. It is to them, not believers, Maher speaks--preaching the gospel of doubt.