The book explores the roots of totalitarian systems, particularly focusing on Nazi Germany and Stalinist Russia. It delves into the historical, social, and political circumstances that led to the rise of these oppressive regimes, including anti-Semitism, imperialism, and the decline of the nation-state. The author further discusses the nature of power, the role of propaganda, and the manipulation of the masses in these systems, providing a comprehensive analysis of totalitarianism.

"The True Believer" is a philosophical analysis of the nature of mass movements and the people who constitute them. The book argues that regardless of the specific cause, whether it be religious, political, or social, all mass movements are interchangeable and their followers are essentially the same. The author suggests that the driving force behind these movements is not the ideology itself, but rather the personal dissatisfaction and frustration of the individuals involved. The book also explores the lifecycle of mass movements, from their creation to their eventual dissolution.