Was Joseph Smith, the founder of the Church of Jesus Christ of Latter-day Saints, "God's anointed messenger"? Or was he "a bone-tossing necromancer, literary hustler and cynical fake"?

The hard question, which might well be asked of the founding prophet of any religion, is left unanswered in James Coates' admirable and readable survey of Mormonism, "In Mormon Circles."

And it is entirely fitting to approach another person's religion with the greatest of deference and respect. By the end of the book, however, we can begin to guess how Coates would respond to his own rhetorical questions.

Coates, a non-Mormon investigative journalist who dares to reveal some of the most arcane secrets and hottest controversies of the Mormon Church, seems to tiptoe through the minefield of his own book.

He is fascinated with the more exotic manifestations of Mormon history and practice, and especially the zealots who stand well outside the Mormon Church. But he adopts a cautious and mostly deferential tone in an apparent effort to avoid offending the adherents of mainstream Mormonism.

With 4 million adherents in the United States--and more than 6.5 million worldwide--Mormonism is "the fastest growing branch of Christianity," already outnumbering the Episcopalians, Methodists and Lutherans. And the Mormon Church, as described by Coates, is a peculiarly American institution, an authentic embodiment of the pioneer spirit, entrepreneurial capitalism and a kind of apocalyptic survivalism.

Coates offers a brief survey of the history of Mormonism, which he presents as a kind of manifest destiny of the spirit. It is a fascinating narrative of the heroic struggle of Joseph Smith, Brigham Young and the band of "Saints" who built a new Zion in the wilderness of the Far West.

"What Carnegie was to steel and Mellon to banking," Coates explains, "Young was to 19th Century American religion."

Coates peers into the secret chambers of Mormon belief and ritual and reveals some of the curious articles of faith non-Mormons often find so odd and off-putting: God as sexually active man living on a distant planet, a universe filled with invisible "spirit babies" yearning to be born into human bodies and then progress into gods, and the now-disavowed but still potent doctrine of "blood atonement."