NASHVILLE, Tenn. (RNS) For Nathan De Lee, going to church as a kid was an ordeal.

De Lee, a Unitarian Universalist, grew up in rural Kansas, where members of his faith were few and far between. Attending services meant an overnight trip to Kansas City, Mo., where the nearest Unitarian Universalist congregation was.

Today, getting to church is easy for De Lee, an astronomer at Vanderbilt University. He's a regular in the choir on Sundays at First Unitarian Universalist Church in Nashville, which has a congregation of about 500.

De Lee is one of a growing number of Unitarian Universalists, a group of people who believe in organized religion but are skeptical about doctrine. The denomination grew nationally by 15.8 percent from 2000 to 2010, according to the Association of Statisticians of American Religious Bodies.

Although they remain small in total numbers with about 211,000 adherents nationwide, Unitarians believe their open-minded faith has a bright future as an alternative to more exclusive brands of religion.

They might be right, said Diana Butler Bass, author of "Christianity After Religion: The End of Church and the Birth of a New Spiritual Awakening." Bass, who has studied thriving progressive churches, said Unitarian Universalists can fill a niche in conservative religious cultures such as the Bible Belt.

"I think there is a role for these kinds of more open and liberal spiritual groups," Bass said. "They provide a nice countercultural community."

The denomination, which started in New England, has been growing more in the South than in other parts of the country, said Rachel Walden, a public witness specialist from the Boston-based Unitarian Universalist Association.

The church hopes to appeal to the rising number of "nones" — those with no specific religious identity. A recent poll from the Pew Research Center for the People and the Press showed that about one in five Americans falls into that category.

Lee Barker, president of Meadville Lombard Theological School in Chicago, said Unitarian Universalists are in the right place at the right time.

"We are at a time when the values of our church and the values of our culture are intersecting," said Barker, who is a Unitarian minister. "I don't see that going away any time soon."

Gail Seavey, minister at First Unitarian Universalist in Nashville, said some of her more conservative neighbors aren't sure what to make of her faith. Some think that inclusive means anything goes — but that's not the case, she said.

Instead of a common theology, Unitarian Universalists have a set of common values. They believe in the worth and dignity of every human being, she said.

That belief in the individual choice in faith can be seen in a Unitarian practice known as water communion. In most other churches, communion bread and wine start in a common vessel and then are passed out to church members. In water communion, everyone starts with a cup of water and pours it in a common bowl.

"We are a bunch of individuals finding our own path — but we are doing it as a group," De Lee said.

In Tennessee, Unitarians grew by 20.8 percent from 2000 to 2010. During the same time frame, they grew by 22 percent in Georgia and by 42.5 percent in Colorado.

Anthony David, minister of the Unitarian Universalist Congregation of Atlanta, which has about 1,000 members, says that Unitarians would rather be kind than right.

"In our tradition, you get to be wrong," he said. "God is big. God is magnificent. You can't tell me that we know everything there is to know about God yet."

First Universalist Church of Denver, where Sunday attendance has increased by 10 percent a year for the past three years, uses an approach called "passive evangelism" to reach newcomers.

That means helping people with their spiritual journey, not on persuading them to become Unitarians, said Kirk Loadman-Copeland, the church's senior minister.

"People come and they are compelled by what they experience, so they come back," he said.

Mark Coppenger, professor of Christian apologetics and director of the Nashville campus of Southern Baptist Theological Seminary, said he wasn't surprised to hear that Unitarian Universalists are growing.

Coppenger said he's sure that those inclusive groups are made up of nice people who would be good neighbors. Even so, their take on faith is wrong, he said.

"Just because you are drawing a crowd doesn't mean you are saying something that is true," he said.

(Bob Smietana also reports for The Tennessean in Nashville.)