The Brazilian government believes there are far fewer Mormons in the country than the LDS Church does.
The 2010 Brazilian census found that 225,695 people identified as Latter-day Saints whereas the LDS Church reported 1,138,740 members in Brazil in 2010.
"These findings indicate that self-identified Latter-day Saints on the census account for only 20 percent of total membership officially reported by the church in Brazil," writes Matt Martinich, an independent LDS researcher. "Furthermore, the percent of official LDS membership self-affiliating as Latter-day Saint on the census has declined over the past decade."
In 2000, the census reported 199,645 Latter-day Saints, or 26 percent of Mormon membership reported for that year (775,822) by the Utah-based Church of Jesus Christ of Latter-day Saints.
To Martinich, who lives in Colorado Springs, the "most concerning finding" was about the LDS Church's growth rate.
The church reported that Brazilian "membership increased by 362,918 members between 2000 and 2010 yet the censuses for these two years indicate a mere 26,050 increase in self-identified Latter-day Saints," Martinich wrote on his blog. "In other words, the increase in census-reported Latter-day Saints was only 7 percent of the membership increase reported by the church."
The numbers were "surprising," Martinich said in a phone interview. "The church has experienced such steady congregational and stake growth over the last decade, especially the past five years."
That's a trend the LDS Church noted as well.
"A good indicator for membership growth and activity in any area can be found in the construction of meetinghouses and temples," church spokesman Scott Trotter said Monday. "We only build them where members need them, not in anticipation of future growth. Our construction of both types of buildings in Brazil continues at a brisk pace."
Because he doesn't know Portuguese, Martinich, project manager for the Cumorah Foundation, which tracks LDS growth, couldn't read background on Brazil's census to know if there was any difference in the data collection this time around.
In many Latin American countries, for example, only the head of household fills out the census forms, he said. "If the father is Catholic, and his wife and children are Mormon, he might fill out the form as if everyone is Catholic."
Still, the numbers are concerning, said Martinich, who is Mormon.
"We know that the church is struggling to maintain self-sufficiency in Brazil, with Brazilians staffing all 27 missions. The church can't do it, even with all the members they have."
During the same period, the census revealed that Protestants have experienced major growth reflected in both church-reported members and census-reported members. In the past 30 years, the Brazilian census has revealed that the percentage of Protestants in the population jumped from 6.6 percent to 22.2 percent.
It is clear, Martinich said, that the LDS Church continues to have "significant convert-retention issues in Brazil."