Pope Francis on Thursday opened the door to the possibility of ordained female deacons for the first time in centuries, potentially signaling a historic shift for the role of women in the male-dominated ministry of the Roman Catholic Church.

The pope is on record as opposing female priests. But, in off-the-cuff comments to an international conference of nuns in Vatican City, he said he supports the creation of a commission to examine whether women should be “reinstated” as deacons.

He called for such a commission to review the history and scope of female deacons who served the church in ancient times. But while suggesting he would welcome a fresh debate, Francis stopped short of saying whether he would ultimately support the readmission of women as deacons, who are vested with a range of priest-like powers including baptism, officiating at weddings, distributing Holy Communion and preaching at Mass.

The pope’s comments came as part of a question-and-answer session during a gathering of the International Union of Superiors General, a 500,000-member global nuns group.

“What impedes the church from including women among permanent deacons, just as it happened in the early church?” the pope was asked, according to a transcript by the National Catholic Reporter. “Why not construct a commission to study the issue?”

The pope told the sisters that, to his knowledge, the women’s role in history “was a bit obscure.” It was not clear, he said, if they were “ordained” — or officially appointed. Creating a commission to study the question “would do good for the church to clarify this point. I am in agreement.”

The pontiff’s remarks were received enthusiastically. The nuns group “is very happy for the welcoming conversation with the pope. It was very friendly, familiar. It was a real dialogue,” said spokeswoman Patrizia Morgante.

Almost immediately, Catholic experts from all points along the ideological spectrum began debating the significance of the comments.

“I can’t underscore enough how groundbreaking this is for the Church,” said Boston College theologian James Bretzke. “If women can be ordained as deacons, then this is going to weaken — not destroy — but weaken significantly the argument that women absolutely are incapable of being ordained as priests. So this is opening more than a crack in the door.”

Yet some liberal female theologians were quick to focus on the ambiguity of the pope’s words. A commission that primarily studied the historical role of women as deacons in centuries past, they warned, could yet mean a long road ahead before women could actually be ordained as deacons today.

“The issue of female deacons has already been studied in depth,” said Marinella Perroni, a Rome-based theologian. “I hope we don’t start from scratch now.”

And Susan Selner-Wright, a conservative philosophy professor at St. John Vianney Theological Seminary in Denver, said that liberals hoping that the pope’s commission would lead to the ordination of women as deacons or priests “will be disappointed.”

“That’s not up to the Church to change,” Selner-Wright said. “It’s up to Jesus. . . . If he had wanted to recruit women to be among the apostles, he would have done it. He just didn’t.”

However, she said that she could conceive of a revised role in which deacons, both male and female, dedicate themselves to service but are not ordained. “There would be really a seismic shift in the understanding of the diaconate and the understanding of deacons. And maybe that would be a good thing,” she said.

The pope’s comments came during a two-week period that saw women’s issues raised more than usual within the male-dominated walls of Vatican City.

One week ago, Cardinal Pietro Parolin, the Vatican’s secretary of state and a close confidant of the pope, said that theoretically, there is no reason why a woman could not one day fill his job.

Parolin — often viewed as the most powerful figure in Vatican City after the pope — made that statement as the Vatican unveiled an overhaul of a section for women in its official newspaper, L’Osservatore Romano.

Francis has spoken out against gender inequality in other veins, for instance calling the pay gap between men and women who do the same job “pure scandal.” In an institution that has been occasionally uncomfortable in addressing the question of women’s role in the church head-on, he has also seemed to facilitate a broader debate. Last year, for example, the Vatican hosted a number of conferences focused on women, including one titled “Women’s Cultures: Equality and Difference.”

But while Francis had elaborated on the need for a greater role for women in the church, he has categorically ruled out the notion of ordaining female priests. As recently as September, he told reporters on a flight back to Rome after his historic visit to the United States that the ordination of women “cannot be done.”

“Pope St. John Paul II after long, long intense discussions, long reflection said so clearly,” the pope said. “Not because women don’t have the capacity. Look, in the Church, women are more important than men because the church is a woman. It is “la” church, not “il” church. The Church is the bride of Jesus Christ.”

Church leaders have been talking about the questions surrounding female deacons for years. A 2002 Vatican commission called for a “ministry of discernment” within the church to sort out what female deacons did in the past and how that relates to the present.

The Vatican’s communications office expanded on the historic role of deacon in the church and the pope’s remarks in a later email.

Until the 5th century, it noted, both male and female deacons flourished in the Western Church, but the role of deacon declined over the next several centuries, surviving only as an intermediate stage for male candidates preparing for priestly ordination. Following the Second Vatican Council, the Church restored the role of permanent deacon, which is open to single and married men.

“Many experts believe that women should also be able to serve in this role, since there is ample evidence of female deacons in the first centuries, including one named Phoebe who is cited by Saint Paul in his letter to the Romans,” said an email from English-language press officer the Rev. Thomas Rosica. Francis “said understanding about their role in the early Church remained unclear and agreed it would be useful to set up a commission to study the question.”

However, the report also noted that when the pope was asked about women preaching homilies during Mass — which deacons do, as do priests — Francis “said it’s important to distinguish” between different types of speaking, and that speaking during Mass connects the role of priest to the person of Jesus, who was male.

Sister Simone Campbell, a prominent progressive U.S. nun who leads the domestic social justice lobbying firm NETWORK, said she views Francis as “kind of caught” between coming from a culture dominated by images of men as leaders and his own inclinations to create strong bonds with women and view them as leaders, too.

Despite references in the New Testament and in early church art to women’s leadership, “there are 1,000 years of saying women’s leadership never happened,” Campbell said. “Part of it is lifting up scriptural references that have been glossed over and moving the church along to accept it. You know how it is for human beings — we see what we expect and don’t see what we don’t want to see. I think that’s what’s opening up . . . the effort to look at the deeper truth.”

Stefano Pitrelli in Rome contributed to this report.

This post has been updated.

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