For centuries, the words "Vatican" and "intrigue" have gone hand in hand. But the Holy See's centuries-old code of secrecy ensured that scandals and conspiracies usually remained hidden behind the tall and sturdy Renaissance walls of the headquarters of the Roman Catholic Church, unbeknownst to the faithful masses around the world.Now, in the era of social media and the 24-hour news cycle, mudslinging between rival church factions is being waged out in the open."It's as if the Borgias and the Medicis had Twitter accounts," Christopher Bellitto, a professor of church history at Kean University in New Jersey, told the National Catholic Reporter.The power struggle has been simmering ever since the Argentine-born Jorge Maria Bergoglio became Pope Francis in 2013. He signaled a break with his two predecessors by promoting a message of mercy over strict dogma, of inclusion over punishment.The anger of a traditionalist faction critical of the pope's more welcoming church broke out into the open for the whole world to see last weekend, with the publication by conservative Catholic media outlets of a bombshell letter by a former Vatican diplomat. The letter was released just as the pope was on a highly charged visit to Ireland — ground zero in the clerical sex abuse crisis.The vitriolic 11-page letter by Archbishop Carlo Maria Viganò, the Vatican's former ambassador to the United States, is filled with innuendo. Mixing factual and ideological claims, it accuses Francis of knowing and ignoring allegations of sexual misconduct by the recently disgraced Theodore McCarrick, the former archbishop of Washington, D.C., who resigned as cardinal last month. In the letter, Viganò calls on the pope to step down for complicity in covering up crimes.In the unprecedented attack, Viganò makes numerous unsubstantiated claims. He says that in 2013, he personally informed the new pope that McCarrick had been widely accused of inviting seminarians into his bed and that Francis' predecessor, Pope Benedict XVI, had punished McCarrick by forbidding him to celebrate Mass in public, give lectures and travel. Benedict, he says, ordered McCarrick to dedicate himself to a life of prayer and penance. Viganò claims that Francis overruled those sanctions and virtually rehabilitated McCarrick.The wrinkles in Viganò's claim are that there is no public knowledge that Benedict ever issued any kind of sanctions against McCarrick and that it contradicts the historical record. McCarrick was often seen celebrating Mass, visiting Rome and attending events with Benedict. It is possible that the former pope did impart those orders secretly and for some reason was unable or unwilling to enforce them.The known fact is that when credible allegations recently surfaced that McCarrick had abused a minor, it was Francis who elicited his resignation as cardinal — an extremely rare occurrence in the Catholic Church.Viganò's letter, titled "Testimony," also contains accusations of cover-ups by about a dozen cardinals who served under Pope Benedict XVI and St. John Paul II when he was pope — many of whom Viganò has clashed with in the past. It makes no mention of the fact that Viganòhimself once tried to quash a probe into a Minneapolis archbishop being investigated for misconduct with seminarians.That Vatican officials have covered up clerical sex abuse is an open secret.It is public knowledge that during John Paul II's papacy, one of the cardinals named in Viganò's letter — former Vatican Secretary of State (equivalent to Prime Minister) Angelo Sodano — long protected the Rev. Marcial Maciel Degollado, a Mexican priest who founded the Legion of Christ. Maciel, who died in 2008, turned out to be a serial predator of minors and was removed from active ministry by Benedict.On Tuesday, Pennsylvania Attorney General Josh Shapiro — who headed the biggest-ever U.S. investigation into clerical sex abuse, uncovering seven decades of abuse of more than 1,000 victims by some 300 priests — said his office had evidence the Vatican knew about cover-ups. But he could not verify whether Francis had direct knowledge of the crimes.The Viganò letter rarely mentions children — the prime victims of clerical sex abuse. Rather, it reads like an ideological screed, a homophobic manifesto. The retired archbishop belongs to a traditionalist church faction, critical of what it decries as Francis' gay-friendly agenda. Those traditionalists blame clerical sex abuse on the presence of homosexuals in the church and believe Francis is too lenient with gays.Viganò calls for the eradication inside the church of what he calls "homosexual networks which ... act under the concealment of secrecy and lies with the power of octopus tentacles and strangle innocent victims and priestly vocations and are strangling the entire church."Most secular experts reject the identification of homosexuality with pedophilia as retrograde and encouraging anti-gay bigotry.Francis and his supporters in the church mostly blame clericalism — a sense of superiority, exclusion and entitlement among the clergy that distances them from the laity — for creating a culture where the crimes of pedophilia are committed.On the flight back to Rome from Ireland Sunday evening, reporters asked Francis two key questions — whether it was true that Viganò had told him about McCarrick and whether Benedict had issued sanctions on McCarrick.Francis answered neither question, dismissed the letter and told reporters to read it and judge for themselves.One of the pope's closest aides, the Rev. Antonio Spadaro, editor of the Vatican-approved Civiltà Cattolica, tweeted that Francishas never publicly "defended himself against the accusations ... because he *knows* that sooner or later the truth will surface."Nevertheless, those crucial questions are still hanging, unanswered, which has emboldened the pope's critics. Many of those critics are in the United States, where conservative Catholics are among Francis' strongest opponents for his stands on climate change, against laissez-faire capitalism and in favor of protection of migrants and refugees — as well as his opening to Cuba and to divorced Catholics.Referring to Viganò's allegations, Bishop Joseph Strickland of Tyler, Texas, told his diocesein a letter, "I will lend my voice in whatever way necessary to call for this investigation and urge that its findings demand accountability of all found to be culpable at the highest level of the church."And, commenting on the Viganò letter, the ultraconservative Rome-based Cardinal Raymond Burke, an American, told the conservative Catholic website LifeSiteNews, "After the truth of each declaration has been established, then the appropriate sanctions must be applied both for the healing of the horrible wounds inflicted upon the Church and her members, and for the reparation of the grave scandal caused."In 2016, Burke and three other cardinals wrote a public letter known as the dubia("doubts" in Latin), in which they accused Francis of sowing confusion on moral issues.Viganò himself has a reputation as a disgruntled prelate with an ax to grind. In 2012, detailed letters he wrote to Benedict accusing other prelates of financial corruption were leaked to the Italian media and led to the Vatileaks scandal that is said to have persuaded Benedict to step down as pope.While Viganò presented himself as a whistleblower, many inside the Vatican began to question his credibility. As Vatican ambassador to the United States from 2011 to 2016, Viganò took active part in the "culture wars." That proved his undoing.During Francis' visit to the U.S. in 2015, the ambassador orchestrated a meeting between the pope and Kentucky county clerk Kim Davis, who had been jailed for five days for refusing to issue same-sex-marriage licenses because of her religious beliefs. News of the meeting — which contrasted with Francis' message of inclusion — broke days later and reportedly infuriated the pope, who summoned Viganò back to Rome.In the days since Viganò's latest bombshell, more details have emerged as to how his letter came about. Marco Tosatti, a conservative Italian journalist who has covered the Vatican for many years, told the Associated Press he helped Viganò write the letter and that he persuaded the former archbishop to make it public after the Aug. 15 release of the Pennsylvania grand jury report.Tosatti saysViganò has gone into hiding to avoid the media onslaught and told the New York TimesViganò was "worried for his own security."Another person who appears to have encouraged Viganò to speak out is Timothy Busch, a conservative American Catholic on the board of governors of the media network that owns the National Catholic Register, one of the outlets that first published Viganò's letter.Busch toldthe New York Times, "Archbishop Viganò has done us a great service" and said the National Catholic Register's leaders "had personally assured him" that Benedict had confirmed Viganò's account, the paper reported.But the retired pope's secretary, Archbishop Georg Ganswein, told a German newspaperthat reports that Benedict had confirmed Viganò's letter "lack any foundation."On Tuesday evening, quoting close aides of Francis, the Italian news agency ANSA reported that the pope is "embittered" by the Viganò letter but "is not contemplating a resignation."Even before the Viganò letter was released, clerical pedophilia in many countries around the world had become the biggest crisis of Francis' papacy, with survivors of abuse demanding the pope undertake much more concrete steps to hold accountable those bishops who ignored or willfully covered up predator priests. Conservatives, meanwhile, based their attacks on the pope on doctrinal issues.Now, after the letter's release, Francis' opponents have raised the stakes, trying to de-legitimize him by accusing the pope directly of covering up sexual abuse. The battle lines have been drawn — the weapon is the issue of clerical sex abuse; the target is the papacy of Francis. The next battleground is likely to be the Youth Synod, a major meeting of Catholic bishops from all over the world, to be held in Rome in October. Copyright 2018 NPR. To see more, visit http://www.npr.org/.