Gossip and internal politicking are so much a part of Vatican life that an old Rome joke goes: “In the Church, a secret is something you only tell one person at a time.”

But this week the definition of secret-spilling got blown up.

Two Italian journalists — an economics reporter for a prominent newsweekly and a muckraking TV figure — published books that used extensive leaked Vatican data to show in detail the kind of financial irregularities that in the past have come out in dribbles and rumors. And the alleged findings are dramatic, from the top Vatican official whose swanky Rome penthouse was refurbished by a church charity to the Vatican pension fund’s $800 million hole, to a report that Vatican real estate is worth about seven times as much as is reported on balance sheets.

Even for a place accustomed to leaks, this week produced a torrent, including surreptitiously made recordings of Pope Francis — a barrier Vatican-watchers said had never been crossed before. For an institution long accustomed to some standard of deference, one thing is becoming clear: The Catholic Church is in a new era.

“Cardinals living in fat apartments for free — we’ve known that since the dawn of time. But this is a new level of stuff spilling out. It’s the Catholic version of people-have-the-right-to-know,” said John Allen, a longtime reporter on the Vatican and Catholicism who is associate editor of Crux, a Catholic site owned by the Boston Globe. Of the Vatican, Allen said: “I think they’re living in a world that doesn’t exist anymore.”

Vatican officials obviously want to deter the kind of extensive leaks that fueled Emiliano Fittipaldi’s “Avarizia” (“Avarice”) and Gianluigi Nuzzi’s “Merchants in the Temple,” and Monday announced they’d arrested two insiders on suspicion of leaking. One was a Vatican bureaucrat and monsignor; the other an Italian PR maven called “the pope’s lobbyist.”

The Vatican arrested a public relations expert and a cleric for leaking confidential documents in connection with two critical books out this week. (Reuters)

The Vatican’s Secretariat for the Economy Thursday issued a statement about the books, saying they “appear to have included false and misleading claims” about the spending of Cardinal George Pell, the secretariat’s chair. Finally and for the avoidance of doubt about the commitment of Cardinal Pell to cost management and control, the Secretariat completed the year well below its 2014 budget and was one of the very few entities to propose a reduction in spending in 2015, the statement read.

Neither reporter, interestingly, is part of the Vatican’s extensive press corps, dozens of journalists called “Vaticanisti.” But recent years have been unusual at the Vatican, with Pope Benedict launching and then Pope Francis continuing a major effort to reform the bureaucracy — in particular the Vatican’s finances. These partnerships have brought in an unprecedented number of secular consultants from firms like McKinsey & Co., the KPMG international accounting firm and the Promontory Financial Group into the orbit of the Vatican, meaning dozens more outsiders have access to internal files, and many on the inside are stirred up in ways that might make them want public attention.

Francis also created a new high-level cardinal advisory board nicknamed C9 for the nine cardinals who are members.

“There is definitely more coming out, because there are more documents to be leaked. We’ve never before had a C9 and KPMG and Promontory and mountains of studies,” said Philip Pullella, a senior Reuters correspondent in Rome for more than three decades. Leaking goes in cycles, he said. “We were in a bear market and now we’re in a bull market. Now things will get a bit more difficult [for journalists.] But things will come around again. You have to remember this is the Vatican, and Italy; we’re in the land of Machiavelli.”

Despite the arrests, it’s not clear who Nuzzi and Fittipaldi relied upon, though both said their sources included clergy and lay people.

Fittipaldi, who writes for the newsweekly L’Espresso, suggested that his book was made possible by the desire for more expansive reforms.

“For 2,000 years the church has always tried to wash its dirty laundry behind its holy walls. And even in recent years, regardless of the announced new transparency that was supposed to wipe out economic and financial scandals, corruption and personal enrichment, the Vatican tried to keep the skeletons hidden in the closet,” he told The Post. “There are sources, especially for what concerns my book, who decided that transparency shouldn’t remain a promise. Too many scandals to uncover, even in the age of Francis, too many enemies aspiring to boycott Francis’s difficult reforms. Too many fake reforms.”

There were many references in the books to COSEA, a commission Francis established a few months after his March 2013 election in order to suggest economic reforms.

This is the third book on the Vatican by Nuzzi, a TV journalist who has a sensational style of writing but whose work has had a massive impact. He was a central figure in a 2012 scandal called Vatileaks, reporting from leaked documents about financial improprieties and infighting. Many Vatican watchers believe Nuzzi’s reporting on the out-of-control bureaucracy may have in part led to Pope Benedict’s historic resignation, and the prominence at Pope Francis’s election of the topic of economic reform. Everyone knew there were power struggles, but he added concrete detail.

Problems were well-known. “These are the reasons Francis was instituting the reforms,” said John Thavis, recently retired after covering the Vatican for many years for the Catholic News Service.

What’s new, Thavis and others agreed, is Francis.

“He’s a high-profile newsmaker of great interest to many people because he’s doing things differently,” Thavis said.

Francis said when he was elected that the Vatican’s inner-workings needed far more transparency, and he was secretly quoted — according to Nuzzi’s book — as demanding more openness after finding “unofficial budgets” that itemized money allegedly misused by Vatican officials.

But others don’t see a dramatic change in openness.

“The very positive tone of coverage [of Francis] gives an impression of openness because there’s more coverage, but there’s more coverage because there’s more interest,” said the Rev. John Wauck, a former political speechwriter who has taught communications at the Pontifical University of the Holy Cross in Rome. “The only really noticeable change is the heightened [media] interest in the Vatican.”

There have been some dramatic leaks in the modern church. In the 1960s a commission created by Pope John XXIII to study birth control created a report in which a majority of members recommended accepting the practice. It leaked out and was published. A year later Pope Paul VI issued the encyclical Humanae Vitae, affirming the church’s official ban on all forms of artificial

Fittipaldi’s publication, L’Espresso, has published so many leaks in recent years that it’s become almost a tattle sheet for Vatican followers. L’Espresso got an early copy of a major papal document this spring, in which Francis argued about the dangers of climate change and overconsumption. It also ran a leaked letter from several cardinals complaining to Pope Francis of liberal interference in the pope’s meeting last month on family issues.

Allen said the sentiment about whistle-blowing is a bit different at the Vatican than for reporters covering, say, a major corporation or the White House.

“From their point of view it’s not principally a matter of policy but of spiritual loyalty,” Allen said. For such leakers, “you inject a degree of moral agony or something.”

Stefano Pitrelli contributed to this story from Rome

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