To its harshest critics, Unitarian Universalism is a religion like ''Seinfeld'' about nothing.
There are no required rituals. There is no church doctrine. Members don't even have to believe in God to belong.
But for centuries, most members have shared principles: They've been committed to progressive movements, from abolition to gay rights.
Now a group of churchgoers, including some political conservatives, is accusing the denomination of replacing spirituality with social activism. They're forming a rival organization to attract like-minded Unitarian Universalists.
The split has manifested itself as a trademark lawsuit over who has the right to the name American Unitarian Association, but the real divide is over the definition of religion.
''To a non-Unitarian Universalist, the idea that there needs to be a major effort to restore God to religion is oxymoronic,'' said David Burton, a 41-year-old lobbyist and co-founder of the maverick group. ''But in many Unitarian Universalist congregations, and at the Unitarian Universalist Association, it is sometimes controversial to talk about God and the divine.''
The Rev. John Buehrens, president of the Unitarian Universalist Association, the Boston umbrella group for the denomination, argues Burton and his supporters are driven by politics.
''They claim a theological motive, but when you have a paid conservative lobbyist at the core of it, you wonder,'' Buehrens said.
The debate moves to Cleveland when the Unitarian Universalists, with 220,000 members, hold their annual meeting starting Thursday.
Burton chose the name American Unitarian Association when he incorporated his group in his home state of Virginia. The Unitarian Universalist Association sued, arguing the name, which they never registered as a trademark, became their property in 1961 when Unitarians and Universalists merged.
''They are appropriating to themselves the Unitarian Universalist Association's history and goodwill and tradition,'' said Edward Leibensperger, the attorney representing the UUA.
The case also raises questions about who has rights to millions of dollars the Unitarian Universalists have been collecting from trusts established in the name of the American Unitarian Association. Burton said he would be willing to sign away any legal right to those funds.
The Unitarians, with roots in a movement that rejected Puritan orthodoxy in New England, are famously resistant to dogma. They have considered removing any reference to ''God'' from their principles. They debate whether to describe their houses of worship as churches or even call themselves a denomination.
Unitarians support a free search for spiritual truth. Atheists and pagans are a significant part of their membership. Jews, Buddhists, Christians and others sometimes join to maintain their traditions without having to accept, wholesale, their denominations' creed.
Members say Unitarian Universalism is the only religion that allows them to change theology without changing churches.
''Almost all of us went through a long period of agnosticism and atheism,'' said the Rev. Carl Scovel, who led the Unitarian Universalists' Kings Chapel in Boston for nearly 40 years. ''We feel a sense of identity, a sense of sympathy, with those raising questions about conventional religion.''
That questioning has led the denomination to take liberal positions on hot-button religious and political issues over the years.
The Universalists ordained their first female minister in 1863. Churchgoers were among the more active supporters of the civil rights movement. They have backed gay rights since 1970, and not only endorse same-sex unions, but some churches also offer the couples premarital counseling.
Yet some Unitarians fear their denomination has become nothing more than a political debate club.
''It's a matter of how open do you become to all beliefs?'' said Roger Finke, a Penn State University sociologist. ''It's hard to justify: why are we a religion?''
Burton was raised in a Baptist church, joined up briefly with the Methodists, then was baptized a Presbyterian before marrying a Jewish woman and deciding to join the Unitarians.
He said he was drawn by the diverse views in his Florida congregation. But when he moved to the Washington, D.C., area in 1995, he found the sermons more often concerned federal legislation than faith.
''There was little talk about spirituality,'' Burton said. ''It became clear to me that that was commonplace throughout the country. The Unitarian tradition was basically being subsumed into a political movement.''
Buehrens sees Burton more as political operative than spiritual seeker. Burton belongs to the Unitarian Universalists conservative forum and, as an attorney and lobbyist, represents Americans for Fair Taxation, which advocates replacement of the income tax with a national sales tax.
Burton was on the Maryland steering committee of 1984 Reagan-Bush campaign and was an adviser to the 1988 National Republican Platform Committee.
But Burton said his politics are irrelevant.
''That's not what we're about,'' he said. ''We're about reinvigorating the Unitarian religious tradition.''
Buehrens questioned why Burton did not follow the lead of others in the denomination to form an affiliate group, such as the Unitarian Universalist Christians or Unitarian Universalist Humanists, under the UUA umbrella.
Burton felt that approach would have been ineffective.
''The Unitarian Universalist Association has a very distinct point of view and a very strongly held belief that the way they're doing it is right,'' he said. ''They want to defend the proposition that Unitarian Universalism is largely about social witness, or social action or social justice.''
About 20 people attended his group's first meeting last year. Burton hopes to recruit 1,000 supporters by year's end and vows to continue with his movement even if he loses use of the denominational name.
The legal case is expected to be decided within several months, but the debate about whether there is enough God in Unitarian Universalism will likely never be settled.
''We're cantankerous,'' Scovel said. ''We love a good argument.''