In the wake of a summer of sexual abuse scandals in the Catholic Church, topped this weekend with an explosive letter alleging that Pope Francis himself covered for an abusive cardinal, American Catholics are agitating for major changes in their church.

Perhaps for the first time, Catholics of all political stripes who protected their hierarchy through what had once seemed the worst of the sexual abuse crisis are training their ire on it. They are calling publicly for bishop resignations, Robert S. Mueller-like investigations, and boycotts of Mass and donations. Even the biggest fans of Francis and his reformist agenda are now questioning whether he is actually part of the problem.

“This is a different reaction from the laity than I’ve ever seen before,” said Adrienne Alexander, the founder of a nascent national movement called Catholics for Action that has staged protests in seven cities in the past two weeks, with more planned in the coming days. “Regular old church folks in the pews are saying: This bishop has to go. Or: All bishops have to go. That’s just something I’ve never seen from the laity.”

And with the biting 11-page letter by Archbishop Carlo Maria Viganò on Saturday, in which the former Vatican diplomat to Washington called for Francis’s resignation, some Catholics are voicing despair about the path forward.

“The hope of reform on this issue: If it can’t be achieved under Pope Francis, who can it be achieved under?” asked Christopher Jolly Hale, who helped lead Catholic outreach for President Barack Obama and has until recently been a prominent supporter of Francis. He added: “No one with good conscience can really defend him with his record on sexual abuse. It’s been an absolute disappointment.”

Viganò’s inflammatory yet unverified letter alleges that Francis’s predecessor, Pope Benedict XVI, secretly sanctioned Cardinal Theodore E. McCarrick for sexually harassing young priests and seminarians but that Francis let the sanctions slide. He also obliquely implicated D.C. Cardinal Donald Wuerl in covering up the behavior of McCarrick, who last month became the first cardinal in history to resign as a result of sexual abuse allegations.

In a statement Monday, the Archdiocese of Washington said Wuerl “has categorically denied that any of this information was communicated to him.” It added: “Archbishop Viganò at no time provided Cardinal Wuerl any information about an alleged document from Pope Benedict XVI with directives of any sort from Rome regarding Archbishop McCarrick.”

The letter from Viganò “shoots the lack of trust right up the ladder,” said Joseph Capizzi, a professor of moral theology at the Catholic University of America. “As a lay person, and I think I speak for a lot of people, we no longer trust these men anymore.”

But although the pain and anger are shared by so many Catholics across a wide spectrum of beliefs, parishioners’ opinions on what caused the sexual abuse crisis — and what remedies the church should pursue to address it — split sharply along ideological lines.

The letter itself is proving to be a kind of Rorschach test for a Catholic Church already painfully divided between left and right, Francis and Benedict, openness and orthodoxy.

Conservatives who have long mistrusted Francis found credible Viganò’s claims. They agreed with his interpretation of the sexual abuse crisis, that it largely stems from the problem of gay men in the priesthood. To this group, Viganò, a fierce Francis critic who as apostolic nuncio to the United States focused on fighting Obama’s Affordable Care Act and legalizing same-sex marriage, is a brave whistleblower showing that Francis needs to exit so the orthodox church can be purified.

More liberal Catholics called for caution before accepting Viganò’s accusations and rejected homosexuality as an explanation for the prevalence of sexual abuse by priests. Some blamed the requirement that priests be celibate, the lack of female priests and other opportunities for female leadership, and overly high respect for priestly authority. To this camp, Viganò’s hyperpartisan writing style, and alleged record of covering up abuse himself, reveal his testimony as part of a conspiracy to bring down Francis.

But even Francis’s most fervent admirers, and Viganò’s most skeptical critics, have been troubled by the letter — by Francis’s handling of recent sexual abuse scandals, including a crisis in Chile, and a massive Pennsylvania grand jury investigation of child abuse by more than 300 priests over 70 years.

Perhaps the most striking development has been the sight of American clerics speaking out explicitly against the most high-ranking men in the Catholic Church.

At the Shrine of the Most Blessed Sacrament, a prominent Washington parish closely linked to the archdiocese hierarchy, the Rev. Percival L. D’Silva closed his homily on Sunday by calling on Wuerl to resign for his role in overseeing abusive priests in Pennsylvania — and received a standing ovation.

During Sunday evening Mass at Holy Trinity Catholic Church, a well-known Jesuit parish in the District, the Rev. Ben Hawley focused his homily on Viganò’s letter, questioning the former ambassador’s political motives but also whether popes and bishops have been doing enough to root out sexual abuse in the church. The congregation applauded.

Meanwhile, a group of students at Catholic University are calling for Wuerl’s resignation.

And amid the back-and-forth on Twitter, on Catholic blogs and in quiet after-Mass conversations, many of the faithful in the pews said they have been talking and thinking about the crisis nonstop but don’t quite know what to do. Refuse to enroll their children in Catholic schools? Withhold donations, as some have pledged? Pray and fast?

One lifelong committed Catholic lay leader said he wrote for the first time to the leader of a religious community that ran a school where he was the victim of sexual misconduct, which he had never reported before.

Hale and others called for three actions: for the church to release all of its secret documents on abusive priests; for federal investigators to consider a criminal case on a major scale; and for U.S. bishops to resign. High on that list is Wuerl, whose conduct during his 18 years as bishop of Pittsburgh figures prominently in the Pennsylvania grand jury report.

Missouri is opening a similar investigation of clergy sex abuse allegations in the St. Louis area, and parishioners in other states are clamoring for such inquiries.

“A lot of us don’t trust the bishops to sort through these things themselves. Lots of people seem to be welcoming, ironically, secular authority — authorities of the state — to come in and do an investigation that we’re more familiar with and maybe more comfortable with,” Capizzi said.

Alexandra DeSanctis, a writer in Northern Virginia who attends Mass almost daily, agreed, saying: “There’s not any democratic mechanism. We can’t vote to impeach the pope.” Instead, she said that people she knows are organizing a movement to demand that the American bishops open themselves to an independent investigation. “Ideally someone from outside the church — especially now that the pope hasn’t commented” on Viganò’s letter.

The political process is one that many Catholics have never compared to their church before. Bishops and priests weren’t like presidents and mayors; they were holy men. Now, that respect for church authority is draining away.

“I work for a labor union. It’s clear to me what to do when we’re dealing with politicians: Vote them out. Put pressure on them in x, y, z ways. As a Catholic, I’d never really expressed frustration in that way,” said Alexander, of Catholics for Action.

She started contacting Catholics nationwide, and soon they began coming to her. The growing network has staged protests in seven cities, including one Sunday outside Mass at the Cathedral of St. Matthew the Apostle in the District, where demonstrators held posters calling for Wuerl’s resignation.

Alexander noted that the people organizing with her are all faithful Catholics, usually every-Sunday types. They don’t want to give up on their church even as they are bitterly disappointed in it.

“I have a good church. A pastor I like who’s a good preacher. We have two wonderful sisters at our parish. We have families with kids my daughter’s age who are going to grow up with her,” she said. “I think that’s what prompting my reaction. You can’t take that away from me. I still want to be part of a church that I think is wonderful.”