The letter was published Wednesday on the website of First Things.

Matthew Schmitz, senior editor at First Things and a signatory of the letter, told CNA that it was written by a “diverse group of Catholics from a whole host of backgrounds.”

The letter’s signatories said their letter was written in part to respond to a Vatican request that young people offer reports on their faith and the role of the Church in their lives, in advance of an upcoming Church synod on young people and vocations.

The letter noted the the signatories were all children in the decades before the public sexual abuse scandals of 2002, and that they are now faithful adult Catholics.

“We ask you to agree to a thorough, independent investigation into claims of abuse by Archbishop McCarrick, both of minors and of adults. We want to know who in the hierarchy knew about his crimes, when they knew it, and what they did in response. This is the least that would be expected of any secular organization; it should not be more than we can expect from the Church,” the letter said.

In June, the Archdiocese of New York deemed an allegation that McCarrick serially sexually abused a minor to be “credible and substantiated.”

Since that initial allegation became public, additional accusations have surfaced concerning McCarrick’s alleged misconduct with adult seminarians, including confirmation of two out-of-court settlements reached with adult-aged accusers by dioceses previously led by McCarrick. Pope Francis accepted Archbishop McCarrick’s resignation from the College of Cardinals July 28.

Schmitz told CNA that the letter was a call for transparency and accountability by the hierarchy.

“We'd like to see light come in. We want an investigation. We want a new attitude on the part of the bishops.”

Such an investigation would be carried out by people not directly connected to McCarrick, and would report to both the Vatican as well as the Catholic faithful, Schmitz said.

Schmitz said the letter addresses a problem that goes beyond the McCarrick allegations. The signatories called for renewed emphasis on the Church’s teachings on sexuality and chastity, as well as “acts of public penance and reparation” by bishops to begin to restore trust among the Catholic faithful.

“I think over the last 50 years in our culture, with the sexual revolution, there's been a sense that the Church needs to broadly accommodate itself to sexual sins,” said Schmitz.

“McCarrick, I think, shows one of the possible outcomes of that accommodation.”

Schmitz warned of a slippery slope if the Church were to change or ignore her teachings on sexuality, bringing up the example of St. Peter Damian, an eleventh-century Benedicte monk, who confronted sexual sins in his own community. The saint recognized that sexual sins compound on another, explained Schmitz, suggesting there exists such a possibility in the contemporary Church.

"I don't think that this crisis would have happened had the Catholic community not succumbed to various sins and made compromises with the flesh," he said.

The letter emphasized this point: “As Catholics, we believe that the Church’s teaching on human nature and sexuality is life-giving and leads to holiness. We believe that just as there is no room for adultery in marriages, so there is no room for adultery against the Bride of Christ. We need bishops to make clear that any act of sexual abuse or clerical unchastity degrades the priesthood and gravely harms the Church.”

Schmitz also cited the recent accusations of widespread sexual abuse and misconduct in Honduras’ national seminary, as well as claims from former seminarians in the United States.

He said that there is a prevailing attitude among bishops to mitigate or dismiss the severity of abuse against adult men, and that this also must change, and that the laity have a duty to make their objections to this behavior known.

"I think the laity should make itself heard and let the bishops know that it is an act of abuse for a bishop to molest the seminarians,” said Schmitz.

“Even if any of these acts were perfectly consensual, they are contrary to the Church's teaching and so profoundly scandalize the faithful."

The letter expressed gratitude for “the way good priests and bishops lay down their lives for us day after day. They say the Mass, absolve us from sin, celebrate our weddings, and baptize our children. Through their preaching, teaching, and writing, they remind us that Jesus Christ has conquered evil once and for all. Their daily sacrifices give us blessings of infinite worth. For all of this, we are profoundly thankful.”

However, Schmitz said an investigation should consider those clerics who have been negligent in uncovering sexual sins among the clergy, along with those who know about misconduct and failed to act. An investigation is needed to ensure a focus on individual responsibility, said Schmitz, and it should not simply result collective statements of fault and regret, as that would dilute the failings of those most responsible.

It is not acceptable for a bishop to plead ignorance, he said, as they are part of the Church hierarchy and must be accountable.

"A shepherd is supposed to protect his sheep, and if the wolves come and attack them, he can't simply say, 'well, I was asleep.'"