ST. LOUIS (RNS) As hundreds of nuns met here on Wednesday to begin crafting an answer to Vatican demands that their leaders toe the line on orthodoxy, there was a pervasive sense that this week's discussions could lead to a fateful juncture in the history of Catholicism in America.

"As you know, this is an assembly like no other assembly we've had," said Sister Pat Farrell, a Franciscan from Iowa who heads the Leadership Conference of Women Religious, which represents most of the 56,000 nuns in communities across the country.

"I suspect we're in for a lot of surprises," Farrell told the sisters as she opened the LCWR's annual meeting.

The options under consideration by the 900 nuns -- several hundred more than have attended recent gatherings -- range from asking the Vatican to continue the dialogue to shuttering the LCWR and reorganizing the leadership body of sisters into a group that would be beyond the Vatican's control.

But that would also signal a historic shift in a church in which the nuns for centuries simply did the work that the bishops preached about -- serving the poor, caring for the sick, and educating the young.

If the showdown reaches such a pass, it would be the latest in a series of dramatic developments since last April, when the Vatican announced that an investigation of the LCWR, authorized by Pope Benedict XVI, had concluded that the group was infected with strains of "radical feminism" and was focusing on social justice issues at the expense of promoting Rome-sanctioned doctrine on issues like abortion and gay marriage.

The Vatican appointed a team of three U.S. bishops, led by Seattle Archbishop Peter Sartain, to take control of the LCWR by reforming its statutes and overseeing its activities.

But the move prompted such widespread outrage at the Vatican and such an outpouring of support for the nuns that it may have changed the political dynamics of a relationship in which the sisters have no canonical power.

In fact, a number of leading bishops have privately assured the nuns of their support while others have increasingly praised them publicly.

"We Catholics love the Sisters!" New York Cardinal Timothy Dolan, president of the U.S. Conference of Catholic Bishops, wrote in a blog post on the eve of the LCWR meeting that effusively praised the nuns and voiced confidence that they would survive the "examination by Rome."

Similarly, in a welcoming address to the LCWR on Tuesday, St. Louis Archbishop Robert Carlson went out of his way to praise the work of the sisters and their influence on his own life. In referring briefly to the LCWR's standoff with Rome, Carlson cited as a model the conflicts between Apostles Peter and Paul in the early days of the church.

"They managed to work things out then, and I pray that you will work things out now," he said.    

Sister Sandra Schneiders, a leading New Testament scholar and spiritual writer, admitted that the sisters were surprised and gratified by the surge of support for their efforts to raise questions within the church that apparently many other Catholics are also asking.

"We thought we were doing our little bit," Schneiders said. "We didn't realize how much was riding on our experience."

On each table in the hotel meeting room where the sisters are gathered in downtown St. Louis the LCWR staff had scattered a dozen or so of the thousands of letters of support they have received and testimonials to the role of the nuns in many lives.

More than just a psychological shot in the arm, that support also seems to have emboldened the sisters to compose a forceful response that would let Rome know that the nuns are tired of decades of criticism and that they are not going to blindly comply with the hierarchy's demands.

What form that response will take remains unclear.

"I don't think they're seriously saying 'Let's walk away,' but they're raising those questions," Sister Theresa Kane, a former LCWR president, told the National Catholic Reporter on Tuesday.

What was apparent from the opening day's session -- the assembly concludes on Friday -- is that the nuns are committed to moving ahead with the kind of changes that they have embraced since the reforms following the Second Vatican Council in the 1960s. The sisters believe those changes better reflect the imperatives of the gospel, while the hierarchy often sees them as innovations that heedlessly upend tradition.

The very title of the assembly summed up the difference in approach: "Mystery Unfolding: Leading in the Evolutionary Now." And the keynote speaker was Barbara Marx Hubbard, a futurist and promoter of "conscious evolution" who is hailed by New Age gurus like Deepak Chopra even as she channels many Christian thinkers.

Indeed, Hubbard's address on Wednesday was replete with what some would consider standard bromides of pop spirituality and what others would value as eternal spiritual profundities. Either way, the sisters of the LCWR welcomed her sweeping panorama of impending change, and in particular their place in it.

"You are the best seedbed I know for evolving the church in the 21st century," Hubbard told them. "That may be a surprise to the world."