Criticism of Earth thoroughly reassesses Marx and Engels’s engagement with theology, drawing on largely ignored texts. Thus, alongside ‘opium of the people’, Hegel’s philosophy of law, and the Feuerbach theses, other works are also central. These include Marx’s early pieces on theology, continual transformations of fetishism, and lengthy treatments of Bruno Bauer and Max Stirner. Engels too is given serious attention, since he moved beyond Marx in appreciating theology’s revolutionary possibilities. Engels’s Calvinism is discussed, his treatments of biblical criticism and theology, and his later writings on early Christianity’s revolutionary nature. The book continues the project for a renewed and enlivened interaction between Marxism and religion, being the fourth of five volumes in the Criticism of Heaven and Earth series.