Christian theism held sway for a long time in the West, but intellectual unity was broken at the dawn of the early modern period. This break was caused in part by numerous philosophical and theological quarrels (“family squabbles” and even “religious wars”) among Christians. Many began to feel both that the quarrels were pointless and that the supernatural claims of Christian theism were no longer tenable. Indeed, reason (as opposed to revelation) began to be viewed as the real and sole source of knowledge.

The idea, central to the theistic worldview, that the world as created by God was “rational, orderly, knowable” and that human beings had the capacity to study and know the world around them led to the development of modern science (37). (This view eventually won out over a Platonic Christian view according to which matter was something inferior to be transcended.) In particular, scientific thinkers began to conceive of the world as a “huge, well-ordered mechanism, a giant clockwork” (37). Deism was born as a philosophy that posited the existence of God, but without the specific claims of revealed religion. Historically, claims Sire, deism was the “result of the decay of robust Christian theism” (41).