Alamy

MORE than 1,200 Lutherans gathered last month in Geist, north of Indianapolis. Lutheran CORE, the conservative group that planned the meeting, had been forced to impose a limit on the numbers. But the pews were packed, the extra chairs claimed, the doorways crowded. In August the Evangelical Lutheran Church of America (ELCA) had voted to let gays in committed relationships serve in the clergy. Congregations would be able to recognise lifelong gay couples. Lutheran CORE was horrified. At Geist, a bishop from Ohio took to the pulpit and asked the meeting's main question: “stay or go?”

Efforts to bring equality for gays have had a tumultuous course in America's legislatures, courts and voting booths. However nowhere is the controversy more painful than in its churches. The ELCA's assembly in August marked a turning point, and the outcome is still uncertain. Lutheran CORE may split away to form a new denomination. Some smaller congregations have, indeed, already left. The church itself is struggling to put August's votes into practice. Some hoped that its leaders would create new rules for pastors by November. On October 6th the church said that deadline would be missed.

America's moderate, “mainline” Protestant churches, such as the ELCA, Episcopal, Presbyterian and United Methodist denominations, have grappled with homosexuality for more than three decades, explains Wendy Cadge of Brandeis University. The Episcopal church has seen the most turmoil. Since a gay bishop was consecrated in 2003, a few dioceses and many parishes have abandoned the church. But the march towards gay equality continues, slowly. In July the Episcopal church affirmed that all ordained positions are now open to gays.

The ELCA offers a new test for how a church might open its doors to gay clergy. With 4.6m members—making it more than twice the size of the Episcopal church—and a powerful concentration in the Midwest, the ELCA sits squarely in the religious mainstream. August's votes followed eight years of careful debate about sexuality, complete with study guides for congregations and, in 2008, more than 110 hearings. Recognising that consensus will be elusive, the ELCA's changes allow flexibility for congregations that disapprove. The hope is that the church will remain intact, despite its deep disagreements.

However, acrimony is inevitable. Those at Geist proclaimed that the ELCA was undermining the authority of scripture. Lutheran CORE has already adopted its own constitution and is now considering whether to form a new denomination. At least a dozen congregations have already left to join Lutheran Congregations in Mission for Christ, a small association of conservative churches.

The fear is that this will accelerate a broader trend. Like other mainline Protestant churches, the ELCA's membership has shrunk, by 10.5% from 1998 to 2008. Art Ellingsen, who was at the meeting at Geist, grew up attending a Lutheran church in Chicago. He says most of his childhood friends now attend Willow Creek, an evangelical behemoth in Chicago's suburbs.

Others argue, however, that the ELCA's decisions can only help to make the church bigger and more vibrant in the long term. Brian Hiortdahl, a pastor on the north side of Chicago, explains that his church's support of gays has already attracted a new generation. Young parishioners now outnumber the old. Melody Eastman has had unlikely success as a Lutheran pastor in Wheaton, Illinois, home to America's best Evangelical college. She says that since her church began actively welcoming gay members, it has attracted both gay and straight couples, keen to be part of an open congregation.

So some may leave the church, and others may come. More than a quarter of Americans have left their childhood denominations, according to a 2007 Pew survey. Nevertheless, Mark Hanson, the ELCA's presiding bishop, prays for unity. “There's an art today to acknowledge how deeply held are the differences, but not let differences devolve into divisions.”