 Tilley described the book as "arguably the most important investigation of the epistemology of mysticism from a sophisticated analytical-pragmatic perspective" since James's "The Varieties of Religious Experience" (1902), and essential reading for theologians and philosophers of religion.He considered Alston's argument "elegant and comprehensive", but concluded that it did not ultimately warrant conclusions stronger than those of James, and found it unclear who Alston intended to convince.Nevertheless, he credited Alston with clarifying the issues involved in the justification of religious belief.