Although most historians have sought the roots of atheism in the history of “free thought,” Alan Charles Kors contends that attacks on the existence of God were generated above all by the vitality and controversies of orthodox theistic culture itself. In this first volume of a planned two-volume inquiry into the sources and nature of atheism, he shows that orthodox teachers and apologists in seventeenth-century France were obliged by the logic of their philosophical and pedagogical systems to create many models of speculative atheism for heuristic purposes. Unusual in its broad sampling of the religious literature of the early-modern learned world, this book reveals that the “great fratricide” among bitterly competing schools of Aristotelian, Cartesian, and Malebranchist Christian thought encouraged theologians to refute each other’s proofs of God and to depict the ideas of their theological opponents as atheistic. Such “fratricide” was not new in the history of Christendom, but Kors demonstrates that its influence was dramatically amplified by the expanding literacy of the seventeenth century. Capturing the attention of the reading public, theological debate provided intellectual grounds for the disbelief of the first generation of atheistic thinkers.