In breaking down barriers restricting gays and lesbians from the pulpit, the nation’s largest Lutheran denomination has laid down a new marker in a debate over the direction of mainline Protestant Christianity, a tradition that once dominated American religious life.

“We’re going to be living in tension and ambiguity for a longer time, partly because the culture has shifted,” said David Steinmetz, a Duke Divinity School professor of Christian history.

The question is whether the mainline church will shift alongside, or if it will decide that the more welcoming attitude toward homosexuality is wrong, he said.

The ELCA – the nation’s seventh largest Christian church – reached its conclusion after eight years of study and deliberation. That culminated Friday when the church’s national assembly in Minneapolis struck down a policy that required any gay and lesbian clergy to remain celibate.

The assembly also signed off on finding ways for willing congregations to “recognize, support and hold publicly accountable lifelong, monogamous, same gender relationships.” The church fell short of calling that gay marriage, but conservatives see that as the next step.

While congregations will not be forced to hire gay clergy, conservative ELCA members decried the decisions as straying from clear Scriptural direction and warned that defections are likely.

Presiding Bishop Mark Hanson pleaded for unity, appealing to both those who long felt marginalized and thought the changes were overdue and those “who feel they were once more central but now feel more peripheral.”

“It would be tragic if we walked away from one another,” Hanson said minutes after the vote.

The ELCA hopes to avoid the kind of fissures that have strained the Episcopal Church and the broader Anglican Communion, of which the 2.1 million-member Episcopal Church is the U.S. branch.

Just weeks ago, Episcopalians approved a resolution saying that “God has called and may call” gays in committed relationships to ordained ministry in the church, defying Anglicans who urged restraint.

The Presbyterian Church (USA) has inched closer to joining the Episcopalians and Lutherans, but the latest effort to undo a policy requiring chastity of gay clergy was defeated this year.

The nation’s largest mainline denomination, the United Methodist Church, has moved in the opposite direction, hardening its opposition to non-celibate gay clergy.

That’s likely to continue because of declining Methodist membership in the Northeast and on the West Coast and growth in the South and Sunbelt, said Steinmetz, of Duke. The church also has a burgeoning presence in Africa, a source of conservatism in the Anglican battles, also.

The ELCA’s move is especially jarring and significant because “it is viewed by all of us as one of the more Reformation-rooted, broadly orthodox denominations” and takes its theology seriously, said Richard Mouw, president of the multi-denominational and evangelical Fuller Theological Seminary in Pasadena, Calif.

“It’s a huge, huge departure for a church like that,” said Mouw, who has urged fellow conservatives in the Presbyterian Church (USA) to stay in the fold despite concerns about a leftward shifts on sexuality.

He said one possible outcome is a “new ecumenical dialogue on the right” uniting beleaguered conservatives from various denominations – though not under the banner of a new one.

Barbara Wheeler, a former president of Auburn Theological Seminary in New York who is now director of the school’s Center for the Study of Theological Education, praised the ELCA for laying a theological foundation for Friday’s vote by first approving a broad social statement on sexuality.

“It’s a completely theological argument toward openness to the possibility of faithful, committed same-sex relationships,” said Wheeler, who has played a central role in gay clergy deliberations inside the Presbyterian Church (USA). “What you’re seeing is two things: The society is in the process of changing its collective mind about the moral status of same-sex relationships, and there’s a parallel theological movement.”

If gays and lesbians can stick it out in mainline churches whose official teachings “were dismissive of their faithfulness and even their personhood,” so can disappointed conservatives, she said. One of the mainline’s strengths, she said, is to be a big tent.

“When you ask what religion has to contribute to the wider society, one hopes at least some religious groups will give examples of how to hold things together,” she said.

Mainline churches are trying to hold together at a time when Americans’ loyalty to denominational affiliation and organized religion is fraying. More Americans are joining non-denominational churches, which tend to be more conservative, or are discarding institutions altogether to craft their own spirituality.

From 2001 to 2008, mainline Protestants dropped from just over 17 percent to 12.9 percent of the population, according to the American Religious Identification Survey, released this year. The study also found that nearly 39 percent of mainline Protestants consider themselves born-again or evangelical Christians – a group likely to push back on liberal stances on sexuality.

Though unity is the goal of many mainline leaders, the future is more likely to hold not a half-dozen large and divided mainline churches but 25 smaller and stronger churches, said Mark Jordan, a Harvard Divinity School professor.

“I think we’re coming up on an epic reorganization of religion in the United States,” Jordan said. “What we’re going to see going forward is more and smaller churches, loosely organized and federated around a progressive pole or a conservative pole.”

Conservative ELCA members have warned of damaged relationships with Lutherans in other countries. While Lutherans in Europe and Scandinavia are to the left of the ELCA on homosexuality, African and Asian Lutherans have been taught a more conservative line by missionaries and theologians, said the Rev. Conrad Braaten, senior pastor of Church of the Reformation, an ELCA congregation in Washington, D.C.

Braaten is optimistic the ELCA can hold together through the sexuality tensions.

“This particular discussion has been going on with a lot of deep feelings in the Lutheran church, but not a lot of acrimony and not a lot of bridges being burnt,” he said. “I think that’s going to make a difference.”