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Churches with firm theologies, door-to-door evangelizing and high expectations for member involvement continue to grow in the United States, even as mainstream Protestant faiths keep losing members, according to the National Council of Churches.

The Jehovah's Witnesses remained the fastest-growing denomination, followed by the Seventh-day Adventist Church. The Utah-based LDS Church was the fastest growing of the 10 largest faiths.

The Jehovah's Witnesses, the 20th-largest denomination, swelled by 4.37 percent from 2008 to 2009 for a total of 1,162,686 members, according to numbers reported to the council last year and included in a newly released 2011 yearbook.

The Seventh-day Adventist Church grew by 4.31 percent and moved into the top-25 denominations, with 1,043,606 members.

In Utah, members of both denominations say the most robust growth has been among Spanish-speaking members, including immigrants from Mexico and Central and South America.

"Our person-to-person ministry has a big impact," said Francisco Montano, a spokesman for Spanish-speaking Jehovah's Witnesses in northern Utah.

The number of Spanish-language congregations has exploded, Montano said, from one in Ogden 30 years ago to 26 between Logan and Spanish Fork today.

Martin Emslie, pastor of West Jordan Seventh-day Adventist Church, says the number of Spanish speakers has eclipsed English speakers in his faith's Utah congregations.

That growth reflects a need, he says.

"Many people are looking for meaning and stability in a world in turmoil."

The Church of Jesus Christ of Latter-day Saints remained one of the fastest-growing U.S. faiths, although its rate slowed to 1.42 percent, according to the new yearbook.

The LDS Church reported 6,058,907 members in the United States in 2009, making it the fourth-largest denomination, the same spot it has held for several years.

David Stewart, a researcher of Mormon growth, said the council's research method — allowing churches to report their numbers — is flawed because the comparisons end up being "apples to oranges."

While the Jehovah's Witnesses and Seventh-day Adventists report active, involved members, the LDS Church claims fallen-away Mormons as well.

"We keep people on the rolls forever, until they die or are excommunicated," he said. "So the church-claimed statistics can be a little unhelpful."

The Catholic Church, which increased by 0.57 percent, remains the largest denomination by far, with 68,503,456 members.

The second-largest, the Southern Baptist Convention, continued its slide, losing 0.42 percent of its members and falling to 16,160,088.

Carson Mencken, a sociology professor at Baylor University in Waco, Texas, said it's no surprise that "high tension" churches — those with strict theologies and expectations that members will be active — generally do better in attracting and keeping members.

"Low tension" churches are those that allow more latitude in beliefs and place fewer expectations on members. Those are the ones declining in size.

The Presbyterian Church (USA) slipped 2.61 percent to 2,770,730 members; the Episcopal Church declined 2.48 percent to 2,006,343 members; and the Evangelical Lutheran Church in America was down 1.96 percent to 4,542,868 members.

The Rev. Eileen Lindner, editor of the yearbook, said the trends remain the same as in recent years. However, she said in a news release: "The rates of both growth and decline have generally slowed."

The National Council of Churches' numbers don't reflect what is likely one of the largest groups of Christians in the United States: nondenominational.

"Those churches," Mencken says, "are growing like weeds."