(RNS) David Stewart felt ill equipped to preach his Mormon faith in recently opened Russia in 1992, when he arrived there as a young missionary. Sure, he had learned the language, but nothing of the culture he was about to engage.

Stewart’s mission experience didn’t match the breathless tales of international growth he had read about in official church magazines, which, he says, focused on “inspiring stories of exceptional members.”

The earnest missionary also wondered why other religions -- such as Seventh-day Adventists and Jehovah’s Witnesses -- had so many more adherents than Mormonism and seemed to be better at reporting actual membership figures and retaining converts.

Such questions simmered in Stewart’s consciousness until 1999, when he launched the website cumorah.com to collect data on every country, including cultural traditions and LDS retention figures.

After a decade, Stewart, a Las Vegas physician, enlisted the help of Matt Martinich, an independent researcher who was a Mormon missionary in South Korea from 2004 to 2006. Martinich had conducted his own survey of LDS growth and published a blog -- ldschurchgrowth.blogspot.com -- on the topic.

Now the two have produced a 1,900-page, two-volume, exhaustive survey, titled “Reaching the Nations: International Church Growth Almanac 2014.”

The encyclopedic endeavor is based on official reports the Utah-based Church of Jesus Christ of Latter-day Saints gives out every year, information on the faith’s website as well as “literally thousands of reports we have obtained from members and church leaders over the years,” Martinich said.

In the almanac’s introduction, premier LDS sociologist Armand Mauss praised the undertaking’s independence, scope, candor and sources, and predicted it will be seen for years as “the most reliable and indispensable source available.”

It couldn’t come at a more opportune time.

Though both researchers are practicing Latter-day Saints, the LDS Church “cannot vouch for its contents or conclusions,” church spokesman Cody Craynor said. “Official church statistics and related context are continually updated at mormonnewsroom.org.”

Mormon leaders have conceded that member retention remains a problem for the faith and have invested considerable resources in trying to remedy it.

Right now, the LDS Church pegs its global membership at 15 million.

Here are some of the almanac’s findings:

About 30 percent of Mormons worldwide -- or 4.5 million -- regularly attend church meetings.

Between 2000 and 2010, LDS congregational growth was most rapid in Delaware (63 percent), Virginia (33 percent), North Carolina (32 percent), and Texas and Tennessee (29 percent). Congregational decline occurred in Louisiana (down 18 percent), Connecticut and New York (down 6 percent), and New Jersey (down 3 percent).

The Philippines is home to the largest population of Latter-day Saints outside the Americas — 675,166 as of 2012.

Within the past three years, the lowest convert-retention rates have appeared to occur within Latin America, where many nations have experienced no noticeable increase in the number of active Mormons within this period.

A big obstacle to LDS conversions can be the “ethno-religious” ties that particular ethnic groups exhibit toward traditional faiths. Examples include ethnic Greeks with the Greek Orthodox Church, the Fulani people of West Africa with Islam, and ethnic Thais with Buddhism.

The first full-time Mormon missionary from China completed his service in 2006. By the end of 2010, 42 missionaries from mainland China were serving full-time LDS missions, many in the United States and Canada.

In Spain, assimilating Latin Americans and Spaniards into the same congregations presents the most widespread ethnic integration issue. Some congregations with an overrepresented Latin American presence may run into difficulties baptizing and keeping active a Spaniard minority.

The United Arab Emirates boasts an LDS stake, four wards and two branches -- partly because this Persian Gulf nation provides greater religious freedom for Christians than most Middle Eastern countries.

The LDS “Word of Wisdom” (a health code urging Mormons to eschew alcohol, tobacco, coffee and tea) and the “law of chastity” (forbidding sex outside marriage) perhaps present the greatest challenges to new converts and seasoned members.

In sub-Saharan Africa, there have been many instances in which individuals cannot get baptized in some countries because they participate in polygamous marriages per local customs and traditions. These individuals have to divorce polygamous spouses to become Mormons -- apparently a rare move. The LDS Church stopped practicing plural marriage more than a century ago.

Countries with the most members and no LDS temple in place, under construction or announced: Nicaragua (80,605 members), Zimbabwe (23,117), Russia (21,709), Papua New Guinea (21,265) and Puerto Rico (21,174).

(Peggy Fletcher Stack writes for The Salt Lake Tribune.)

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