In The Varieties of Religious Experience, originally delivered as the “Gifford Lectures on Natural Religion” at the University of Edinburgh just over a century ago—and published, to great acclaim, in 1902—William James distinguished two types of judgment he thought appropriate for the study of religion. The first, which he termed “the existential judgment,” concerned the origins, history, and nature of religion; the second, which he defined as “a spiritual judgment,” dealt with the meaning and significance of religious phenomena. Though the first sort of judgment, dwelling on historical facts, might be necessary, its ultimate usefulness was questionable; it couldn’t serve by itself as “a guide to life” nor could it offer any “value for purposes of revelation.” Thus, in applying the first judgment to the Bible, that scripture “would probably fare ill,” he noted,...