The 1869 trial, for fraud, of William Mumler, a Spiritualist photographer whose uncanny images of ghosts watching over his portrait sitters convinced many that science had opened a door to the afterworld, is the narrative engine of Peter Manseau’s The Apparitionists: A Tale of Phantoms, Fraud, Photography, and the Man Who Captured Lincoln’s Ghost (Houghton Mifflin Harcourt, Oct.). The book has belief at its heart; Manseau plays variations on that theme, exploring America’s faith in technological marvels such as photography and telegraphy, as well as the religious ferment of the late 19th century, when Spiritualist mediums promising a “spiritual telegraph” to the hereafter offered a balm for the psychic wounds inflicted on the nation by the Civil War.

“Spiritualism is one of these significant moments in American history we have entirely forgotten, at least in terms of popular memory, or it has been reduced only to parlors and séances,” says Manseau, a scholar of religion and curator of American religious history at the Smithsonian’s National Museum of American History. He notes that digging into the historical record, he realized “just how many people identified as Spiritualists, whether they were also Christians or not.” He adds, “There was a real overlap.” In an America traumatized by the loss of some 850,000 of its sons, the newborn religion spread quickly, he writes in The Apparitionists, extending “from the hinterlands to urban centers, redrawing the map of the nation as a topography of ghosts.”

Looking for a way to tell the story of that cultural moment, Manseau stumbled, fortuitously, onto the Mumler affair. “My kids were interested in history, and we were doing a lot of Civil War traveling,” he recalls on the phone from his home in Annapolis, Md., “so I was thinking about these Civil War photographers, some of whom were moving bodies around on the battlefield, creating these images that were shaping the nation’s impressions of the war”—the original fake news.

Fakery loves credulity—a disbeliever’s name for belief—and the two dance a pas de deux in The Apparitionists. Manseau’s cast of characters includes the Fox sisters, whose girlhood poltergeist pranks begat the religion of Spiritualism and who later admitted it was all a hoax that got out of hand; the Civil War photographers Mathew Brady and Alexander Gardner, who, as Manseau notes, were not above posing corpses for dramatic effect; and, fabulously, P.T. Barnum, the self-styled Prince of Humbugs, who testified against Mumler because even he thought the ghost photographer’s chicanery was beyond the pale.

In ways Manseau couldn’t have foreseen, The Apparitionists holds up a mirror to our times. In Mumler’s day, photography offered a new standard for irrefutable proof even as it played tricks on the eye. Now, the internet is both history’s greatest repository of knowledge and, at the same time, a petri dish for cultivating conspiracy theories like the Pizzagate hoax propagated via social media. “We are in this moment that’s much like the 19th century, when new technologies challenged us to think about belief and perception and truth in new ways,” Manseau says.

The historian in Manseau can’t resist pointing out that we’re a nation of true believers, and always have been. “We like to believe all kinds of things,” he says. “It makes life interesting.” In the testimony from Puritan witch trials, he points out, “you find these remarkable collections of beliefs that people are jumbling together and calling Christianity—collections of folk beliefs from England mingling with beliefs and practices from the Caribbean and South America and Africa.”

Manseau’s own relationship to belief is rich and strange. As the son of a former nun and a priest who never renounced his vows, he is ex damnato coitu–the fruit of a “damned union”—in the judgment of the Catholic Church. Though officially “under suspension,” his father refused to stop ministering to the urban poor in his storefront church in Roxbury, Boston, an abandoned funeral parlor that still reeked of embalming fluid.

As Manseau recounts in his unsparing tale of family, faith, and broken faith, Vows: The Story of a Priest, a Nun and Their Son (2005), when he “reached the age of teenage dissent” he turned his back on the religion that twined around his family tree like ivy, running through the lives of 300 years’ worth of Irish and French Catholic nuns and priests. “I was driven away from my Catholic upbringing,” he writes, “by a sense that as a family we were in the faith but not of it; a nagging feeling that the church we were raised to place at the center of our lives did not in fact want us.” Later, Manseau learned that both his parents were molested by priests—a revelation that makes their unshakable faith all the more miraculous.

Even though Manseau lost his religion, religion never lost him. It has followed him all his days, from his undergraduate years as a religion and literature major at UMass to “a dissertation on Yiddish literature at a Jesuit university” (as Manseau described his doctoral studies at Georgetown in a New York Times essay) to his current job at the Smithsonian.

All of Manseau’s half-dozen books touch on religion, in one way or another. His novel Songs for the Butcher’s Daughter (2008) is a Chagall painting in prose about the last Yiddish poet in America. Yiddish literature—a “literature written in large part by the disaffected sons of rabbis,” he notes, with a laugh—“really resonated with me as the son of a former priest,” he says. “These Yiddish writers, when they decided that they were trying to get away from their traditional upbringing, they didn’t not write about it anymore; that became the subject of all their stories. That’s the kind of writer I ended up becoming. Though I did not ultimately come to think of myself as a religious person, that became a real driver of everything that I was writing.”

Rag and Bone (2009) is a wry meditation on the power of relics—the severed hand of a nun, a hair from Muhammad’s beard—to electrify the faithful. One Nation, Under Gods (2015), a history of religion in America, quietly debunks the notion that the New Jerusalem among the savages and the mosquitoes was, from the first, a Christian franchise. Even Melancholy Accidents: Three Centuries of Stray Bullets and Bad Luck (2016), Manseau’s collection of black-comedic newspaper items about calamitous mishaps with firearms, directs our attention to acts of God: “People shoot, but it’s God who delivers the bullet” is the book’s deadpan epigraph.

And what does he believe, this lapsed Catholic and son of a former nun and a priest who defied his church? Manseau is thoughtful. Like the American grab-bag version of Christianity, he’s “a product of all my many influences,” he decides. From his Catholic upbringing, he retains a profound sympathy for what scholars call “material culture,” in his case “the prayer cards and the rosaries and the vestments my father kept in the front hall closet, things that served a vital purpose in the most private and important part of the lives of those who were most important to me.” It’s an affinity that serves him well as a curator, telling stories with objects.

Then, too, Manseau believes in language. “One significant part of my upbringing was this understanding that words were a technology that allowed you to access the sacred,” he says. “As much as I found Catholic mass boring when I was young, it still gave me the understanding that we were there to say words in a particular order and that was going to allow us to experience something, and as a child that was very moving. I am an oral writer: I write and then I read it aloud and then I edit it; I’m going for a quality where you feel spoken to.”

Mark Dery is the author of the essay collection I Must Not Think Bad Thoughts (Univ. of Minnesota, 2012) and a forthcoming biography of Edward Gorey (Little, Brown; 2018).