The nation's mainline Protestant denominations have quarreled for years over the role of gay men and lesbians in church life, but those debates promise to grow even more intense and acrimonious this summer.
The conflicts, which come as California and other states wage legal fights over same-sex marriage, could well influence whether some of the religious denominations remain intact or splinter into smaller factions.
California's Supreme Court is expected to rule today on the constitutionality of the state's ban on same-sex marriage. For the faithful in a number of American churches, the hard-fought legal battle over civil marriage for gay and lesbian couples runs parallel to religious struggles that are strikingly similar and often just as heated.
One of the most visible denominational skirmishes will occur in July, when leaders of the 2.2-million-member Episcopal Church consider proposals at their national convention in Anaheim to sanction a religious rite for blessing same-sex unions and ease restrictions on the ordination of gay and lesbian bishops.
If approved, the steps could further alienate theological conservatives, giving them reason to join four Episcopal dioceses and hundreds of parishes that split last year to form a separate church.
The country's largest Lutheran denomination, meanwhile, is scheduled in August to consider a long-anticipated statement on human sexuality that, among various elements, says that Christian tradition recognizes marriage as a covenant between a man and a woman.
Even as they acknowledge deep divisions over homosexuality, members of the 4.7-million member Evangelical Lutheran Church in America will decide at their meeting in Minneapolis whether they should enable local congregations to recognize same-sex unions and allow "practicing homosexuals" in committed relationships to serve in the ministry.
Other Protestant groups are embroiled in similar struggles, including the Presbyterian Church (USA) and the United Methodist Church. Another, the American Baptist Churches USA, is scheduled to hold its biennial convention in Pasadena in June but is not expected to consider any action related to same-sex marriage, a spokeswoman said.
But scholars are watching the Episcopalians and Evangelical Lutherans especially closely, seeing them as a gauge for other denominations. The experts are waiting to see if the intensified debate and turmoil leading up to the national conventions produces any consensus on issues that have long divided U.S. Protestants.
"What has been emerging for the last several years is becoming even clearer now: We're on a trajectory toward the blessing of same-sex unions and the ordination of lesbian, gay, bisexual and transgender people," said the Rev. Jay Johnson, a professor of theology at the Pacific School of Religion in Berkeley and director of academic research at its Center for Lesbian and Gay Studies in Religion and Ministry.
But Johnson added: "It may mean, when there are breakthroughs in these churches, we see more breakaways."
U.S. Christians remain stubbornly split over homosexuality. One recent survey by the Pew Forum on Religion & Public Life found that 56% of all mainline Protestants believe it should be accepted by society. Just 26% of Evangelical Protestants felt that way.
Few denominations have been as torn by the issue as the Episcopal Church, the U.S. branch of the Anglican Communion, a 77-million-member fellowship. Theological conservatives are a minority in the Episcopal Church but a large majority among Anglicans worldwide. The conflict between church liberals and conservatives escalated in 2003 with the consecration of an openly gay priest, V. Gene Robinson, as bishop of New Hampshire. Amid pressure from traditionalists within the U.S. church and Anglican officials elsewhere, Episcopal leaders agreed at their last General Convention in 2006 to urge local church authorities not to consecrate any bishop "whose manner of life presents a challenge to the wider church." Still, 700 conservative parishes in the United States and Canada defected last year and formed a new church affiliated with overseas Anglicans.
Now, as Episcopalians approach their July convention, dioceses around the country are submitting resolutions to ease restrictions on gay bishops and to authorize same-sex marriage blessings. The issue of blessings is now left up to local Episcopal authorities.
The convention's host, the Episcopal Diocese of Los Angeles, has tried to send a message by approving a policy at its December convention that gives local priests permission to officiate at rites of blessing for same-sex couples.
"I think it's about time we get about the business of having marriage equality in the church," said the Rt. Rev. J. Jon Bruno, bishop of the Los Angeles Diocese. "I am waiting with bated breath to see what happens" at the Anaheim meeting.