(CNN) -- The Rev. Paul Earl Sheppard had recently become the senior pastor of a suburban church in California when a group of parishioners came to him with a disturbing personal question.

Rev. Rodney Woo leads a successful interracial church but says church members still clash over race.

They were worried because the racial makeup of their small church was changing. They warned Sheppard that the church's newest members would try to seize control because members of their race were inherently aggressive. What was he was going to do if more of "them" tried to join their church?

"One man asked me if I was prepared for a hostile takeover," says Sheppard, pastor of Abundant Life Christian Fellowship in Mountain View, California.

The nervous parishioners were African-American, and the church's newcomers were white. Sheppard says the experience demonstrated why racially integrated churches are difficult to create and even harder to sustain. Some blacks as well as whites prefer segregated Sundays, religious scholars and members of interracial churches say.

Americans may be poised to nominate a black man to run for president, but it's segregation as usual in U.S. churches, according to the scholars. Only about 5 percent of the nation's churches are racially integrated, and half of them are in the process of becoming all-black or all-white, says Curtiss Paul DeYoung, co-author of "United by Faith," a book that examines interracial churches in the United States.

DeYoung's numbers are backed by other scholars who've done similar research. They say integrated churches are rare because attending one is like tiptoeing through a racial minefield. Just like in society, racial tensions in the church can erupt over everything from sharing power to interracial dating.

DeYoung, who is also an ordained minister, once led an interracial congregation in Minneapolis, Minnesota, that eventually went all-black. He defines an interracial church as one in which at least 20 percent its membership belongs to a racial group other than that church's largest racial group.

"I left after five years," DeYoung says. "I was worn out from the battles."

The men and women who remain and lead interracial churches often operate like presidential candidates. They say they live with the constant anxiety of knowing that an innocuous comment or gesture can easily mushroom into a crisis that threatens their support. Poll: Race and religion in America »

"It's not all 'Kumbaya' and 'We are the World,' " says Sheppard, the pastor of the Northern California church, who was raised by his father, a Baptist preacher, in the black church. "There are plenty of skirmishes."

Can't we just be Christians?

If it's so tough, why bother? That's one of the first questions interracial churches must address.

DeYoung says he encountered many blacks who said they wanted a racial timeout on Sunday.

"They would say, 'I need a place of refuge,'" he says. "They said, 'I need to come to a place on Sunday morning where I don't experience racism.' "

Whites also complained of their own version of racial fatigue, other scholars say.

Theodore Brelsford, co-author of "We Are the Church Together,'' another book that looks at interracial churches, says whites often say that church should transcend race.

"They'd say, 'Can't we just get along without talking about race all the time? Can't we just be Christians?'"

Not really, say advocates for interracial churches. They argue that churches should be interracial whenever possible because their success could ultimately reduce racial friction in America.

American churches haven't traditionally done a good job at being racially inclusive, scholars say. Slavery and Jim Crow kept blacks and whites apart in the pews in the nation's early history. Some large contemporary black denominations, like the African Methodist Episcopal church, were formed because blacks couldn't find acceptance in white churches.

Large denominations like the Methodists, Baptists and Presbyterians split over race in the 19th century when their members clashed over the issue of slavery, Michael Emerson, a scholar on interracial churches, recounted in his book, "Divided by Faith."

But interracial church advocates say the church was never meant to be segregated. They point to the New Testament description of the first Christian church as an ethnic stew -- it deliberately broke social divisions by uniting groups that were traditionally hostile to one another, they say.

DeYoung, the "United by Faith" co-author, says the first-century Christian church grew so rapidly precisely because it was so inclusive. He says the church inspired wonder because its leaders were able to form a community that cut across the rigid class and ethnic divisions that characterized the ancient Roman world.

"People said that if Jews, Greeks, Africans, slaves, men and women - the huge divides of that time period -- could come together successfully, there must be something to this religion," DeYoung says.

Biblical precedents, though, may not be enough to make someone attend church with a person of another race. Something else is needed: a tenacious pastor who goads his or her church to reach across racial lines, interracial church scholars say.

The Rev. Rodney Woo, senior pastor of Wilcrest Baptist Church in Houston, Texas, may be such a person. He leads a congregation of blacks, whites and Latinos. Like many leaders of interracial churches, he is driven in part by a personal awakening.

Woo's mother is white, and his father is part Chinese. He attended an all-black high school growing up in Port Arthur, Texas, where he still remembers what it was like to be a minority.

"Everyone understands the rules, the lingo, the mind-set -- except you," he says. "It was invaluable, but I didn't know it at the time."

When he became pastor of Wilcrest in 1992, he was determined to shield his church members from such an experience. But an exodus of whites, commonly referred to as "white flight" was already taking place in the neighborhood and the church.

Membership fell to about 200 people. At least one church member suggested that Woo could change the church's fortunes by adding a "d" to his last name.

"The fear there was people would think I was Chinese," he says. "There would be a flood of all these Asians coming in, and what would we do then?"

Woo kept his last name and his vision. He made racial diversity part of the church's mission statement. He preached it from the pulpit and lived it in his life. He says Wilcrest now has about 500 members, and is evenly divided among white, Latino and black members.

Woo doesn't say his church has resolved all of its racial tensions. There are spats over music, length of service, even how to address Woo. Blacks prefer to address him more formally, while whites prefer to call him by his first name, (a sign of disrespect in black church culture), Woo says.

Woo tries to defuse the tension by offering something for everyone: gospel and traditional music, an integrated pastoral staff, "down-home" preaching and a more refined sermon at times.

But he knows it's not enough. And he's all right with that.

"If there's not any tension, we probably haven't done too well," he says. "If one group feels too comfortable, we've probably neglected another group."

Going from "they" to "we"

Sometimes, though, a determined pastor is not enough. Interracial churches can also implode on issues far more explosive than worship styles -- like sex and power.

One such issue is interracial dating. Some scholars and leaders who deal with interracial issues say it's not unusual for parents in racially-mixed churches to leave when their teenage kids begin dating.

Woo saw that exodus at Wilcrest. Some parents talked about the importance of a multiracial church, until their kid became attracted to someone from another race within the church.

"As kids began to date, some things get revealed," he says. "They didn't want their kids involved in interracial dating -- and that's not just whites."

Accepting black leadership is another touchy subject. Most interracial churches are led by white pastors. A congregation typically becomes all-black if a black pastor is hired, says DeYoung, the "United by Faith" co-author.

"As long as the top person, the senior pastor, is white, power sort of resides with whites," DeYoung says. "But when that shifts, it does something psychologically to people. People usually leave."

Black pastors who do gain the acceptance of interracial congregations still have to watch themselves. Some white parishioners, even progressive ones, get uneasy when a black pastor gets too fiery in the pulpit, says Brelsford, co-author of "We are the Church Together."

"A black church sermon that could be understood as impassioned might be interpreted as angry and defensive by a white congregation," Brelsford says. "It could kick into fear of black men."

Sheppard, the black minister of the church in California, says he modified his style to appeal to all sorts of people.

He says he abandoned the pulpit pyrotechnics he learned growing up in the black church when his congregation's racial mix changed. He also carries his authority lightly, dressing casually in the pulpit and consulting with church committees before making decisions. In conversation, he's relaxed and accessible.

"I'm very aware of how rare this is," he says of being the black minister of an interracial congregation. "I'm humbled by it."

The people in the pews must also do their share of adapting, scholars and ministers say. Only when ethnic groups no longer feel compelled to abandon their entire culture on Sunday morning can a church claim to be interracial, Brelsford says.

An interracial church isn't one in which all the black members act, dress and worship like the church's majority white members to make them feel comfortable, he says.

Interracial churches resist "taking one dominant identity and forcing everyone to fit into it," Brelsford says.

That appears to have happened at Sheppard's church in Northern, California. Since its rocky early days, it has now grown to a multiracial congregation of about 6,000 people. Whites, blacks, Asians, Latinos - all now attend.

"We refuse," Sheppard says, "to be a one-flavor-fits-all church."

Interracial congregations often include people who probably wouldn't have become friends in any other circumstances. They are people like Dwight Pryor, a black man who grew up in segregated Mississippi seeing blacks brutalized by whites. He says he grew up disliking white people.

Today, Pryor says he is best friends with a white member of Wilcrest, a man who grew up in Alabama during segregation in a family that hated blacks.

When Pryor sees his friend on Sunday, he says he no longer sees a "they" or a "them" trying to invade his world.

He sees his brother in Christ.

"We come to love each other," he says. "When I look into his eyes, I can see the love of Jesus Christ. He and I have become friends."

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