Once atheism emerged, it began to challenge the moral authority of both the Church and the State. Religious doubt inspired the U.S. War of Independence and the French Revolution, while in England the growing campaign for the rights of the working class was led by radical atheist reformers whose work helped to give birth to Socialism. The history of disbelief continues with the ideas of self-taught philosopher Thomas Paine, the revolutionary studies of geology and the evolutionary theories of Darwin. Jonathan Miller looks at the Freudian view that religion is a “thought disorder”. He also examines his motivation behind making the series touching on the issues of death and the religious fanaticism of the 21st century.