This is a reference work unlike any that exists today. It provides a complete and detailed survey of the varieties of agnosticism, atheism, free-thought, humanism, skepticism, and unbelief, as they have appeared historically and on the contemporary scene. Editor Gordon Stein has collected comprehensive biographies of the many prominent men and women associated with free-thought including Charles Bradlaugh and Annie Besant in England, Voltaire and Diderot in France, V I Lenin in the Soviet Union, Thomas Paine, Clarence Darrow, and Robert Ingersoll here in the United States. The "Encyclopedia" brings together 203 articles from all the influential philosophers and psychologists whose thoughts and writings contributed to the growth of religious skepticism and unbelief like Giordano Bruno, Spinoza, Locke, Hume, Kant, Comte, Spencer, Haeckel, Feuerbach, Dewey, Santayana, Freud, Reich, Russell, Sartre, Ayer, Hook, and many others. Stein also contributes a history of organized free-thought, fully discussing political movements and theories that have had a direct bearing on unbelief. He has added perceptive essays on unbelief within the world's important religions: Buddhism; Christianity; Hinduism; Islam; Judaism; and, Taoism. This invaluable reference work is cross-referenced and indexed and contains five comprehensive appendices for meetings, organizations, publishers, periodicals and a bibliography of unbelief. The many contributors include Isaac Asimov, Hazel Barnes, Germaine Bree, Paul Edwards, Antony Flew, Paul Kurtz, Richard Martin, Martin Marty, Kai Neilsen, James Randi and many others.