-- The Vatican's partial rejection last week of the U.S. bishops' zero-tolerance policy on sexual abuse is the latest and clearest sign of what the nation's fastest-growing Roman Catholic lay organization says has been its main concern all along: The church hierarchy is stalling reform, and action lies with empowering people in the pews.

"American Catholics have looked to their bishops for pastoral leadership in a time of great crisis and scandal," Jim Post, the group's president, said in a statement. It was released after the Vatican announced Friday it would work with American bishops to refine the zero-tolerance policy but stopped short of offering full approval. "It is deeply troubling that the Vatican has concluded that the judgment of those closest to the problem and to the 64 million members of the U.S. Catholic community is so severely flawed."

In the wake of the sexual abuse scandal in the church, many lay groups have formed -- some seeking change and others defending the hierarchy. Voice of the Faithful has been perhaps the most controversial because it has tried to walk a narrow line between the two: Its leadership insists it is faithful to church teachings but wants the laity to become more involved in guiding the church.

As a result, Voice of the Faithful is facing increasing opposition from church officials and conservatives who suspect heresy and a hidden agenda. At the same time, the group is struggling to position itself as a credible middle-of-the-road alternative for Catholics with widely divergent views who are seeking ways to democratize the church.

The group, based in Newton, Mass., has spread quickly since its creation earlier this year, with members in more than 40 states and 21 countries. As it grows, it is making many church leaders nervous: Bishops in at least five states have barred affiliates of the group from meeting on church property. Archbishop John J. Myers of Newark labeled its members "anti-church and, ultimately, anti-Catholic."

The Boston Archdiocese recently banned new chapters from meeting on its grounds (although existing chapters are exempt). And Cardinal Bernard F. Law is not expected to accept more than $50,000 in donations from the group, which collected the funds as an alternative to the annual Cardinal's Appeal. The money was offered to the archdiocese last week on the condition that it not be used for administrative expenses.

Some traditional lay groups accuse Voice of the Faithful of secretly pursuing an agenda meant to undermine church teachings and exacerbate schisms within the Catholic community.

"As an organization marketing itself as Catholic, Voice of the Faithful is engaged in consumer fraud," said C.J. Doyle, executive director of the Catholic League of Massachusetts. "Real Catholics don't picket the cathedral and engage in confrontation with the hierarchy."

But many priests have welcomed chapters into their parishes and participated in Voice of the Faithful forums. The Boston Priests Forum, which represents about 300 priests, plans to discuss the church's relationship with the group in a meeting with Law this week. In addition, Oklahoma Gov. Frank A. Keating (R), head of a panel appointed by the U.S. bishops to review church policy, has called on the hierarchy to embrace lay organizations such as Voice of the Faithful.

"They are an extraordinary gift to the church . . . deeply committed to their faith and their church," said Thomas H. Groome, a Boston College theologian.

Voice of the Faithful was co-founded in January by James E. Muller, a Nobel Peace Prize-winning cardiologist, and Jim Post, a lawyer who organized a boycott against Nestle USA in the 1970s for promoting infant formula in Third World countries. Since then, the organization has swelled from 30 parishioners who met in a church basement into a permanently staffed organization with 13 full- and part-time consultants, a Web site, a $200,000 budget and an estimated 25,000 members in dozens of chapters.

Post and others maintain they are committed to church teachings and working with the church to support survivors of clergy sexual abuse and so-called priests of integrity and to shape structural change within the church, including the establishment and strengthening of pastoral parish councils. In doing so, members have invoked the Second Vatican Council of the 1960s, saying it provided for the laity's right and duty to become active in the guidance of their church.

"Our approach is to work from the parish level upwards, both because it is necessary and because it is possible," the group says on its Web site. "We believe that, if we can make our local faith communities models of consultation and openness, analogous changes will follow at higher levels (though slowly)."

Some Catholic lay groups have formed around individual issues, such as seeking the ordination of women or allowing married priests. But Voice of the Faithful has attempted to steer clear of those controversies.

A recent group meeting at St. John the Evangelist Church in Wellesley, Mass., where the group was established, focused on planning a prayer retreat for organization leaders and a listening session with priests as well as discussing finances and young adult outreach.

"We're not radical Catholics, although there are members of our group who are," said Svea Fraser, an interim trustee of the organization.

Nevertheless, some church observers believe the group inevitably will be taken over by more liberal activists.

Conservative Catholics and church observers say that the group's agenda is too ambiguous and that the liberal groups will rush in to fill the void. They note that speakers at the group's inaugural convention in July included the head of an Austrian-based group that supports the ordination of women.

William Donohue, president of the Catholic League for Religious and Civil Rights, the nation's largest Catholic civil rights organization, said it is hard to tell where Voice of the Faithful's agenda will lead.

"I certainly understand the desire for reform and the anger directed at higher-ups for the way this whole mess has been handled," he said. "On the other hand, I am a bit wary. Some of the people involved do have their own agendas. There's no question about that. The question is then, will this remain an organization that is not going to be hijacked by some fringe on the left or the right."

Still, the mounting criticism of Voice of the Faithful could be a sign that the group is being taken seriously by the very people it hopes to influence, said R. Scott Appleby, who studies American Catholicism at the University of Notre Dame.

After Bishop William Murphy of Rockville Centre, N.Y., barred the group from church property, a standing room-only crowd of 600 showed up for a Voice of the Faithful meeting in September, including priests, nuns, deacons and other Catholics, group members said.

"Until there is an alternative for laity to express their frustration with the lack of communication and consultation," Appleby said, "Voice of the Faithful has a future."

Members of Voice of the Faithful -- Mary Scorzoni, front, and Robin Vachon, right -- lead a group of demonstrators as they approach Cathedral of the Holy Cross in Boston after a Voice of the Faithful conference.