Exhuming the long-buried religious roots of our ostensibly godless age, Michael Allen Gillespie reveals in this landmark study that modernity is much less secular than conventional wisdom suggests. Taking as his starting point the collapse of the medieval world, Gillespie argues that from the very beginning moderns sought not to eliminate religion but to support a new view of religion and its place in human life--and that they did so not out of hostility but in order to sustain certain religious beliefs. He goes on to explore the ideas of such figures as William of Ockham, Petrarch, Erasmus, Luther, Descartes, and Hobbes, showing that modernity is best understood as a series of attempts to formulate a new and coherent metaphysics or theology. We're still trying, Gillespie contends, to resolve the tensions inherent in our ideas of God, man, and nature--tensions that arose in the late Middle Ages during a titanic struggle between contradictory elements within Christianity. In the end, Gillespie shows that understanding modernity's continuing entanglement with Christian metaphysics is crucial to comprehending the hidden possibilities of our confrontation with radical Islam and with the dualistic elements of our own tradition.