What if a wedding guest at Cana had tweeted that Jesus didn’t really turn water into wine? Or the children of Israel had IM’ed that they crossed the Red Sea at low tide? Would live data streams shake believers’ faith or simply lead to endless online bickering over who has the true truth? Janet Reitman’s absorbing book on the Church of Scientology identifies the core challenge for new religions: The seams show. It’s the same problem Mormon founder Joseph Smith faced when newspapers reported on his latter-day revelation. Today’s would-be messiahs face a much larger media echo chamber and a much bigger obstacle — globally networked communication that complicates faith, especially when facts suggest that faith may be misplaced.

And the facts Reitman reveals about Scientology are damning. Even if the tradition’s basic practices have helped some people to live fuller lives, the institution itself seems irredeemably corrupt.

Inside Scientology” is a masterful piece of reporting. Reitman, a freelance journalist, supplements Scientologists’ memoirs, founder L. Ron Hubbard’s extensive writings, news reports and declassified online documents with dozens of interviews of former and current church members. She’s one of the few outsiders to have had access to Scientology’s upper echelons and secret sites, a boon granted when she was researching an article for Rolling Stone. Her insights help explain why the movement has intrigued millions since its launch more than 60 years ago.

Reitman’s story starts with Hubbard (1911-1986), a wildly self-assured college dropout who drifted through a series of careers until he tried writing. Gifted with a wild imagination and a strong work ethic, he wrote books in several genres: mysteries, Westerns and adventure tales. When pulp novels did not prove lucrative enough, he moved into the burgeoning field of science fiction. He found his niche in Los Angeles among occultists and fellow fabulists, but after several doomed escapades — including running off with a friend’s lover and life savings — he hit bottom. Refusing psychological help, Hubbard found a way to heal himself. Writing a series of self-assessments, he examined his own psychological state, admitting to lying and exaggeration. Afterwards, he listed his assets: sexual magnetism, magical powers and literary prowess, but foremost an ability to understand others and direct their thinking. Here he found more than a cure; he identified his life’s vocation: “He would use his mind, in other words, to repair his soul. And soon, he would show others how to use their own minds to do exactly the same thing.”

Hubbard outlined his technique in a book, “Dianetics: The Modern Science of Mental Health,” which was published in 1950. His “scientific” alternative to psychotherapy required only a partner, several “auditing” sessions and an investment in his book, which, by the end of the year, had sold more than half-a-million copies. With his newfound wealth, Hubbard extended his organization, but he overspent and overpromised. The fledgling enterprise soon collapsed.

‘Inside Scientology: The Story of America's Most Secretive Religion’ by Janet Reitman. Houghton Mifflin Harcourt. 444 pp. $28. (Houghton Mifflin Harcourt/Houghton Mifflin Harcourt)

Still confident in his product, Hubbard repackaged the “mental science” of Dianetics as the Church of Scientology. Unlike with other congregations, though, salvation came at a price. Scientologists spent thousands of dollars on auditing sessions to become “clear” and to rise in the ranks.

Between the mid-1950s and mid-’60s, the Church of Scientology looked like many other conservative churches, stressing top-down leadership, strict obedience and traditional sexual morality. But no sooner had Time wondered “Is God Dead?” than Hubbard revamped for the Aquarian Age. Scientology went countercultural, promising a drug-free cosmic high. New members bought the vision and paid upfront for every step on the path.

Reitman cites Scientology’s successive reincarnations as evidence of Hubbard’s marketing genius. But the pay-off of the auditing process — access to the religion’s core beliefs — was compromised by the content of those beliefs: trippy sci-fi fantasies concocted by the aging, paranoid Hubbard. Increasingly isolated in his last years, he ceded control to David Miscavige, one of his young lieutenants. Reitman depicts Miscavige, who has spent his entire life within the organization, as highly adept at intimidation. Lacking Hubbard’s gift for reinventing Scientology to suit the times, Miscavige has focused on buying real estate and recruiting celebrities.

In addition to revealing insider information about Scientology’s leaders and celebrities (read how Tom found Katie), Reitman’s book profiles many less visible church members. Jeff Hawkins, a hippie stoner recruited in the ’60s, eagerly embraced the church’s mission of global transformation. He served 38 years in top management positions — until, he claims, Miscavige turned him out with $500 in severance pay. Natalie Walet, a second-generation Scientologist, says there are problems at headquarters but they don’t diminish the value of Hubbard’s teachings. Although many of her peers were pressured to join Scientology’s managerial elite, Walet told Reitman that she planned to attend law school. She is confident, poised and independent, a living witness to Scientology’s stated principle of self-actualization.

Then there’s Lisa McPherson, who joined the church in 1982 at a co-worker’s suggestion. The wife and child of abusive alcoholics, McPherson needed stability, order and community. Scientology provided all three. But by the mid-’90s she stopped making progress in her auditing sessions. Worried about her large debt to the church and confused by its teachings, she grew increasingly disoriented. After a car accident, McPherson stripped naked, and paramedics brought her to a local hospital. Before she could be evaluated, a team of Scientologists whisked her away. Seventeen days later, emaciated and dehydrated, she died in the church’s care.

McPherson’s death and Scientology’s role in the tragedy became the subject of newspaper articles. In the past, the church had tried to intimidate reporters, or anyone else, who appeared critical of the organization. (Reitman’s account of its campaign against the IRS is riveting.) But as information proliferated online, Scientology’s leaders could not exert the pressure they once wielded clandestinely. Former members started blogs describing their experiences in the church, including their participation in harassment campaigns. Some downloaded church membership files or financial statements; others shared secret doctrines and Hubbard’s private writings.

Reitman benefited from this open environment, but she also will be judged by it. She implies that after more than 30 years in the church Hawkins left of his own accord. Yet in his blog, “Counterfeit Dreams,” Hawkins details a leave-taking that was far from voluntary. Reitman also seems challenged by her stated goal of even-handedness. While she quotes many who say Scientology helped them and others who remain positive about the church, her own bias slips in through unguarded adjectives and value-laden phrases, e.g., “an inner stratum that reeks of authoritarian control.” More substantively, the book could have explained more about the church’s theology. Until I read Lawrence Wright’s recent New Yorker profile “The Apostate: Paul Haggis vs. the Church of Scientology,” I did not realize how and why Scientology exerts such a powerful hold on members. Reitman barely mentions the church’s beliefs, doctrines or rituals.

On balance, however, “Inside Scientology” is a compelling introduction to “America’s most secretive religion,” as the subtitle has it. Even for those who have no interest in parsing when cults become religions or why faith upends fact, Reitman tells a spellbinding story of a larger-than-life personality whose quirks, ticks and charisma shaped America’s newest homegrown religious movement.

Janet Reitman will be live online Monday, July 18 at 11 a.m. ET to take your questions about Scientology.

Diane Winston holds the Knight Chair in Media and Religion at the USC Annenberg School for Communication and Journalism.