Reason has always held an uncertain position within Christianity. ""I believe because it is absurd',"" wrote Tertullian in the third century as he dismissed rational thought. For Augustine of Hippo, reason had some merit as a route to faith but otherwise was of limited value, since it could undermine a person's ability to approach God: ""the wisdom of the creature,"" he opined, ""is a kind of twilight."" In seventeenth-century England, reason had...