FAITH, in probably the best-known definition of it, is "the assurance of things hoped for, the conviction of things not seen." Although this definition itself comes from the Christian scriptures, specifically from the anonymous epistle to the Hebrews in the New Testament, it can, mutatis mutandis, be applied across a broad spectrum of religions and religious traditions. Whether or not the term faith appears in those traditions is, at least in part, a matter of how various terms are translated into modern Western languages. More importantly, however, faith is used, even in Judaism and Christianity (where it has been the most successfully domesticated), to cover an entire cluster of concepts that are related to one another but are by no means identical. If there is truth in the contention that faith is the abstract term with which to describe that attitude of the human mind and spirit of...