An overview essay and approximately 50 alphabetically arranged reference entries explore the background and significance of atheism and agnosticism in modern society. This is the age of atheism and agnosticism. The number of people living without religious belief and practice is quickly and dramatically rising. Some experts call nonreligion, after Christianity and Islam, the third largest "religion" in the world today. Understanding the origins, history, variations, and impact of atheism and agnosticism is crucial to getting a grasp of the meaning of the present and gaining a glimpse of the future. Exploring some of the most extraordinary people, events, and ideas of all time, this book provides a fair, comprehensive, and engaging survey of all aspects of contemporary atheism and agnosticism. An overview essay discusses the background and social and political contexts of unbelief, while a timeline highlights key events. Some 50 alphabetically arranged reference entries follow, with each providing fundamental, objective information about particular topics along with cross-references and suggestions for further reading. The volume closes with an annotated bibliography of the most important resources on atheism and agnosticism.