In this book, I have shown that Thomasius's religious beliefs are an important part of his thought, and that they must inform the interpretation of his program for a more general intellectual reform and renewal, on which his reputation as an “enlightened” philosopher mainly rests. Although faith and philosophy were distinct spheres, Thomasius believed that they were, at the same time, closely dependent on each other. A false conception of religious faith threatened to corrupt philosophy. The problem with traditional, orthodox Lutheran theology and its emphasis on doctrine was that it led believers to overestimate the importance of the “head” in relation to the “heart” in human nature. It produced false “scholastic” and pedantic learning and neglected the true wisdom, which required humans to recognize that the source of their moral corruption was the will-as-desire, not the intellect. Although Thomasius's notion of faith did not determine every aspect of his ideas on morality, nature, and history, none of these areas can be explained entirely without it. It was part of his criticism of orthodox Lutherans’ “papalism” and their refusal to grant the Calvinist elector of Brandenburg any say in the administration of their ecclesiastical affairs. Thomasius's history of the church was primarily about the origins of false religious orthodoxy, based on doctrine, which was the foundation of the clergy's authority and power over laymen. His history of Roman law also reflected his preoccupation with the rise of this false orthodoxy, which made use of a distorted version of Christian religion to justify priests’ influence on secular jurisdiction. Thomasius's increasing emphasis on the importance of the passions in his theory of natural law and moral philosophy was closely related to the change in his notion of faith from a theological to an anthropological voluntarism. And his hermeticist interpretation of nature, which explained natural phenomena with reference to powers of sympathy and antipathy between natural bodies, was, as orthodox Lutherans recognized and pointed out, designed to furnish his heretical notion of the will-as-desire with a natural philosophical foundation.