This freshly synthetic work shows how religious choice developed as the backbone of American religious life. In this first book by Lincoln Mullen, the unintended effects resulting from people choosing their own religion become manifest. Mullen exposes these ironies gently and clearly. This is an important book and a pleasure to read.

Mullen takes up one narrative thread after another in the story of how nineteenth-century Americans chose their own religions. The predominant thread is the sinner's prayer. White evangelicals broadcast this prayer for heartfelt conversion in multiple iterations through sermons, Sunday schools, and expansive networks of print media. In response to this outpouring, other groups doubled down on conversion in their own terms and in ways that the evangelicals who disseminated the sinner's prayer did not intend. The fabric of American religious life became more differentiated as a result, even as the pressure to choose became ubiquitous. Americans learned how to think about religion as William James defined it—a “forced, living, and momentous kind [of] option.” (James, “The Will to Believe,” The New World 5 [June 1896]: 327–347). Thus, for Mullen, James's definition, first published in 1896 in the fourth paragraph of “The Will to Believe,” simply codified the psychology of religious experience that had come to prevail in the United States over the course of the nineteenth century.

Building on his argument for the broad dissemination of the sinner's prayer, Mullen considers accounts of religious choosing among the Cherokee. When a small but significant number of tribal members took control over their own churches, Christianity became a Cherokee religion and not simply an expression of missionary influence. Tribal members who opposed conversion to Christianity found themselves in the position of having to choose traditional religion over against Christianity, which meant that the old ways had become optional, too.

As Mullen's discussion of Cherokee agency makes clear, this is not a book about white Protestant imperialism. Nor does it focus on the marginality of minority religions around a central core, as R. Laurence Moore did in his influential Religious Outsiders and the Making of America (Oxford University Press, 1987). In effect, Mullen's book replaces Moore's by showing how the influence of evangelical Protestantism dissolved into a decentralized ethos of religious choice. Promoting conversion as all-important but unable to control its meaning or practice, evangelicals unintentionally helped their rivals grow.

In the most pointed variant of this irony, African Americans converted evangelical Christianity into a religion of emancipation. In their hands, the sinner's prayer morphed into an eschatological plea grounded in experiences and memories of freedom from slavery. The effects of this transformed Christianity, unintended by white evangelicals, were considerable. While no more than a quarter of slaves were church affiliated, and most of them belonged to churches that condoned slavery, by 1916, more than two-thirds of black adults were members of churches governed by blacks. These churches understood conversion toward salvation as the trajectory of transcendence over bondage, suffering, and injustice.

In the hands of Latter-day Saints, the ironic effects of religious choice were less straightforward and more circular. Fed up with the proliferation of religious sects and their competing calls to convert, Mormons chose a restored Gospel meant to supplant all others and finally establish God's kingdom. Through great toil and imagination, the Mormon Church took its place as one among many competing sects, exacerbating the very situation that church founders had sought to overturn.

In his discussion of Jews and Catholics, Mullen's argument reaches further. These groups not only defined conversion in their own terms but they grew in strength further beyond the Protestant orbit. Jews firmly resisted efforts to be converted, defining their own religion in terms of sincerity about ritual practice. Jewish resistance to conversion contributed to group solidarity, even as the emphasis on sincerity made the conversion of others to Judaism difficult to prove.

Catholics defined conversion more expansively as repentance under the authority of the Catholic Church, which recognized the baptism of all Christians. This inclusive Catholic approach to conversion had a subversive effect. As growing numbers of nineteenth-century Americans found the Catholic Church appealing, evangelical efforts to impress the country with the need for conversion had very unintended effects.

The trouble with Mullen's argument lies not in what he says about religion in nineteenth-century America, much of which is insightful and convincing, but in what he does not say about what came afterward. In the twentieth century, anti-communism and free-market fundamentalism captured much of the rhetoric associated with religious choosing. Ironically, the differentiated religious worlds of the nineteenth century became foundations for the political manipulation of people and their choices and churches. Perhaps if Mullen had paid more attention to the enduring economic and political division in the United States caused by slavery, the picture of religion in the nineteenth century would be less positive than he paints it, with the implications for our own troubled time more obvious.

In our own day, the marketing of choice and the politics of conversion are not just ironic aspects of the legacy of the nineteenth-century religions described by Mullen but tragic ones as well. Echoes of the sinner's prayer can be heard in the easy excuses American evangelicals offer for predatory public leaders and in their religious choices to disbelieve in global warming, evolution, and public education. As Molly Worthen wrote in the New York Times, “The struggle to disentangle [evangelicalism] from white supremacy, from misogyny—and from the instinct to defend politicians like Roy Moore—demands sound arguments grounded in evidence” (“Sunday Review,” November 19, 2017, p. 2). It also requires willingness to see how a culture exceedingly respectful of religious choice has led us to this point.