It was an unlikely candidacy: a thirty-eight-year-old mayor from the heartland who pitched himself as the solution to partisan gridlock, played up his military experience, talked often about his faith, and promised to end the country’s moral decline. He was fond of quoting the Founding Fathers, had an army of grassroots supporters, and came from a swing state. But the year was 1844, the state was Illinois, the parties were the Whigs and the Democrats, and the candidate was Joseph Smith, the founder of the Church of Jesus Christ of Latter-day Saints.

Whether or not the country would have been with Joe, we’ll never know: on June 27th, a few months after announcing his candidacy, the first Mormon to run for President became the first Presidential candidate to be assassinated. Smith’s death marked the end of a decisive period in Mormon history, one that is less familiar to most outsiders than the Church’s founding, in New York State, or its eventual move to Utah, where, against considerable odds, its members came to flourish. But the chaotic months of Smith’s Presidential campaign and his effort to establish a theocracy in Illinois are the subject of the historian Benjamin E. Park’s new book, “Kingdom of Nauvoo: The Rise and Fall of a Religious Empire on the American Frontier” (Liveright).

Park’s book is a compelling history, built from contemporaneous accounts and from the previously unreleased minutes of the Council of Fifty, a governing body of sorts that Smith convened in Nauvoo, Illinois, when he was feeling besieged by his enemies and anticipating the Second Coming of Christ. Its minutes help clarify Smith’s sometimes contradictory political theology, and Park’s explication of them elevates “Kingdom of Nauvoo” from pure religious history to the realm of political theory. Park, an ambidextrous thinker, is equally sensitive to the danger the state can pose to religious minorities and to the danger that a religious institution can pose to the secular state. In his account, the early Mormons were a rowdy band of neo-Puritans who mounted a fundamental challenge to the democratic experiment. The tensions that they experienced—between the right to religious freedom and the limits of religious tolerance—still persist today.