What made Smith’s followers stick by him, even after the local Protestants became openly hostile and the Latter-day Saints had to flee from state to state and town to town? One thing—and it seems peculiar to the Mormons—was the thrill of believing in a wholly American revelation. It happened here, to people like us: angels came and told us that the land was not story-less and virgin but ancient and possessed of a secret history. (This meant assigning the native people a made-up past and ignoring their actual past; what to do about the Indians, who were both the “ancients” and the “Others,” became a source of theological and practical grief.) Curiously, the Americanness of the revelation was also one of the things that made it irresistible to the thousands of working-class Englishmen and women who converted to the new faith in the eighteen-thirties and forties; visiting Mormon apostles, led by a promising Smith lieutenant named Brigham Young, told prospective immigrants that “millions upon millions of acres of land lie before them unoccupied, with a soil as rich as Eden.”

The powers that possession of the Book of Mormon conferred mattered more than the doctrines that it contained. “Rarely did missionaries draw on the verses and stories of the Book of Mormon in sermons,” Bowman explains. “Rather, they brandished the book as tangible proof of Joseph Smith’s divine calling.” Some holy texts, the Gospels, for instance, are evangelical instruments meant to convert people who read them; others are sacred objects meant to be venerated. The Book of Mormon is a book of the second sort. As the French religious historian Jean-Christophe Attias points out, in traditional Judaism the physical presence of the Scripture is at least as important as its content: when the Torah is unrolled during the service, it’s meant to be admired, not apprehended. That the Mormons had a book of their own counted for almost as much as what the Book of Mormon said.

Mormonism had other assets. Smith held (especially in the sermons he preached toward the end of his life) that God and angels and men were all members of the same species. “God that sits enthroned is a man like one of you” and “God Himself was once as we are now, and is an exalted man” were two of his most emphatic aphorisms on the subject. (People who were “exalted,” in Smith’s language, were men moving toward godhood, as God himself had once been a man who achieved it.) Although in many other respects, as Fluhman and Bowman point out, Mormonism was orthodox in its outlook—Jesus is the sole Messiah, and his history as told in the Gospels is taken to be true, if incomplete—the doctrine of God-as-Man divided Smith’s cult from the others, and scared the pants off even charismatic Protestantism: the Protestants were willing to accept that we are made in his image, but not that we are made of the same flesh.

This doctrine led in turn to various theological niceties, which seem to have risen and receded in the faith’s theology over the years: one is that the birth of Jesus had to have been the consequence of a “natural action”—i.e., that God the Father knew Mary in a carnal way, in order to produce the Messiah. (This doctrine is currently in disfavor, but it had a long life.) Another is that God, being an exalted man, must have a wife, or several wives, as men do; she is known as the Heavenly Mother, and is a being distinct from Mary. (Smith’s belief in exaltation evolved into the belief that other planets were inhabited by men even more exalted than we are; Smith taught that the truly exalted will get not just entry into Heaven but a planet of their own to run. This is now taken, or taught, metaphorically, the way conventional Christians often think of Hell, but it was part of the story.)

And then the Book of Mormon, unlike anything in the five books of the Torah, is told in a kind of flat first person: the book’s opening chapters all begin with the formula “I, Nephi.” This was not just an American Bible; it was a Bible with an evangelical, camp-meeting tone laid over the Old Testament vocabulary. The testimonial is the essential genre of the Great Awakening, and the Book of Mormon, for all its pastiche, is at heart a testimonial—starting with Nephi’s own account of how he got his people here. Even if you didn’t stay to find out what I, Nephi, did, the fact that I, Nephi, did it counted for a lot. Among other Christian texts, perhaps only the Gnostic Gospels of the early Christian centuries use the first person in quite this way. (Luke and Revelation begin with a personal introduction, but aren’t really personal stories.) And, though the charge of Gnosticism was often directed at them maliciously by other Christians, Mormonism does have a definite Gnostic aroma. Like the Gnostics, the Mormons thought that the conventional texts had too much atonement and too little attainment. Mormonism objects to making a big deal of the morbid agony of Jesus on the Cross at the expense of the more cheerful apparition of Man-made-into-God. This is why there are no crosses on Mormon temples; our guy triumphed far more than he suffered.

America, one might fairly say, had two foundings: the first under the Enlightenment guidance of its rich intellectual founders, and a second with the popular, evangelical Second Great Awakening, which flamed a quarter century afterward. Ever since, the two have, like the Lamanites and the Nephites, been at war for the soul of the country, with the politics not always easily predictable; it was really the Awakening side that led to abolitionism. (Smith ran for President on an advanced abolitionist platform, in 1844.) Over time, the spiritual descendants of the Awakening have sought to annex Enlightenment doctrines, chiefly through the claim that the Founders were not skeptical Enlightenment deists but passionate Evangelical fundamentalists, while the Enlightenment-minded have tried to annex the Awakening’s passionate energy to their causes, as in the civil-rights movement, where black churches became the emotional engine of what was, on its face, a legal argument about public facilities. Mormonism is a child of this fracture. In one way, it is a product of the Enlightenment love of secret histories and societies and rococo cosmologies—a “Magic Flute” for America, sung with a massed choir. (Many of its rituals and symbols seem to have a source in Freemasonry; Smith was an inducted Mason.) But it is also an instance of popular religious turbulence, not at all esoteric in its appeal but fully open to the world and evangelical in spirit.

As Fluhman shows in marvellous detail, Mormonism was the great scandal of American nineteenth-century religion, somewhat as Scientology is today, though Mormons understandably dislike the comparison. Mainstream Protestants couldn’t dismiss Mormonism, couldn’t embrace it, and couldn’t quite understand it, and yet it thrived. For American Protestantism, Mormonism was the other: you defined yourself against those nuts. Indeed, to this day, Joanna Brooks tells us, Mormons perceive their persecutors to be not atheists or secularists, let alone Jews or Catholics, but Protestant Evangelicals. (“And then it happened. My mother put her hand on my knee as we made the turn. There they were, those words—MORMONS: CHRISTIANITY OR CULT?—on the Trinity marquee. Anger burned between my temples again, and tears stung my eyes. ‘I heard they held up garments’ ”—Mormon sacramental underwear—“ ‘in church last Sunday, too,’ my mother told me, pityingly.”)

Forced out of New York by an earlier version of that fierce Protestant hostility, Smith and his followers began their years of wandering. Wherever they went, they infuriated the non-Mormon locals, and also managed to infuriate one another: the early history of the movement involves a bewildering series of excommunications, internal banishments, and the increasing threat of violence to enforce new rules as Smith received them. Smith was eventually martyred by a mob in Carthage, Illinois, while in the local jail awaiting trial for treason. Which of his doctrines enraged the mob is hard to grasp, but it may have been sex more than heresy. You could have as many doctrines as you liked, but not as many wives.

There the story might have ended. Yet as a rule the success of a new religious movement depends not so much on the mystical visions of its founder as on the executive energy of its first evangelist. Christianity may be Jesus’ intuition, but it is Paul’s institution, and the Nation of Islam owed less to the mysterious preachments of Wallace Fard than to the organizational tenacity of Elijah Muhammad. Brigham Young inhabited this role for the Mormons, and about as fully as any apostle ever has. Young was one of Smith’s earliest followers, a hard-bitten character from Vermont who, inheriting Smith’s mantle, got his posse of believers out West and, instead of pushing forward along the Oregon Trail and joining the gold rush, chose an arid but suitable piece of land, planted his people there, and, in 1847, began building a wooden tabernacle in the town he called Salt Lake City.

Young’s accomplishment in getting his unruly congregation out of their contentious place in settled country to a new territory of their own is genuinely remarkable. As the first governor of Utah—he preferred the Mormon name Deseret—he ruled more or less alone over a huge chunk of Western territory, including a lot of what is today Wyoming, Colorado, and Nevada. Understandably, Turner is inclined to see Young as a kind of Western hero, the John Wayne character in a Howard Hawks Western, rough around the edges; he is one of the few nineteenth-century public figures to be routinely on the record saying “frigged” and “shit.” Yet the figure who emerges in the biography starts off more like Jim Jones or David Koresh. He preached a brutal doctrine of “blood atonement” that Turner describes as a “chilling perversion of the golden rule.” Young’s formulation: “Will you love that man or woman enough to shed their blood? That is what Jesus Christ meant.” For a time, he tolerated a group of frontier thugs who acted as personal emissaries, and, despite Smith’s gestures toward universalism, imposed a hard anti-African and pro-slavery line. (Blacks were excluded from the priesthood and from temple ceremonies.) Young was in power at the time of the Mountain Meadows Massacre, in 1857, in which more than a hundred peaceful non-Mormon emigrants were disarmed under an elaborate promise of safe conduct and then murdered en masse. “The attackers mercilessly shot, stabbed, and slashed the throats of emigrants who pled for their lives,” Turner recounts, in an event he describes as “a heinous crime executed after careful deliberation and subterfuge.” For all that, the killers “appeared to remain not just in good standing but in Young’s own personal favor,” Turner notes. It’s a long way to the Osmonds.

Young’s brutality, and his insistence that Utah belonged exclusively to the Mormons, led President James Buchanan to send in the troops; Young armed his men and swore that they would burn down Salt Lake City before they bowed to Washington. All the elements for full-scale religious warfare seemed set, and the thing might easily have ended in a counter-massacre and the collapse of the Mormons as a force in North America.