More than 3,000 people attended the United Church of Christ's General Synod in 2005, and witnessed the mainline denomination's historic endorsement of same-sex marriage.
Attendance at this year's Synod, June 22-26 in Hartford, Conn., is expected to more than double, according to UCC General Minister and President the Rev. John Thomas.
While many are heralding the UCC's 50th anniversary, Thomas readily admits the buzz this year surrounds the Synod's star-studded line-up, which includes Sen. Barack Obama, D-Ill., a UCC member and a top presidential candidate.
"The momentum took off and the energy is building," Thomas said.
Joshua DuBois, the Obama campaign's director of religious affairs, said the senator's Synod speech on Saturday will be his first major address on faith and politics as a presidential candidate.
The address, DuBois said, will combine personal details about Obama's religious experiences with prescriptions for how religious Americans might put their faith into action.
It will also focus on "the growing movement of people of faith" from a variety of traditions, "coming together around our connections as a people and using those connections to address our common challenges," DuBois said.
Shaun Casey, an adviser to the Obama campaign and a professor of ethics at Wesley Theological Seminary in Washington, D.C., said he expects the address to be "as detailed an account of how a person's faith shapes his policies as I have seen from any presidential candidate."
While Obama's star has risen in recent years, his denomination's fortunes have not fared as well.
Traditionally, the UCC, which was born in 1957 from a union of the Evangelical and Reformed Church and the Congregational Christian Churches, has been at the vanguard of progressive causes.
Its forebears were the first mainline Christians to ordain an African-American, and the denomination was the first to ordain openly gay and lesbian ministers, according to the UCC.
But its most recent progressive move -- the 2005 vote to endorse same-sex marriage -- has led to "significant conflict in the church," Thomas said.
About 100 churches have left the UCC since then, according to Thomas. Last year, membership in the 1.2 million-member church dropped 3.8 percent, according to the Yearbook of American and Canadian Churches.
Donations from church members to the UCC's national offices and regional conferences decreased by more than $2 million in 2006, according the church's annual report.
There's a resolution on the Synod's agenda this year to repeal the endorsement of gay marriage, though Thomas said he expects to measure to fail.
Asked if the UCC progressive views on issues such as gay marriage might hinder Obama's ability to reach moderate voters, DuBois said the denomination contains various voices that run the gamut from liberal to conservative.
Moreover, DuBois said, "Senator Obama is not going to distance himself from his denomination, which has a long history of Christian witness, just because he is running for president."
Thomas said he hopes Obama, as well as the other featured speakers such as journalist Bill Moyers, Pulitzer Prize-winning author Marilynne Robinson and actress Lynn Redgrave, will bring a sense of renewal to the UCC.
"Our Synods are always kind of family reunions," Thomas said. "But I really hope this one will be a revival experience and energize people about the UCC."