Author Ed Decker, a former Mormon who has been one of the religion's staunchest critics for decades, says a vast majority of people who convert to Mormonism leave the religion within a year because they realize it's not Christian.
Decker's latest book is called My Kingdom Come: A Mormon Quest for Godhood. He says the Church of Jesus Christ of Latter-day Saints sends out about 60,000 volunteer missionaries around the world -- but most of the 300,000 annual converts, he notes, do not stick around.
"Eighty percent [of converts] actually leave the Mormon church within the first year," states Decker. "They go there thinking this is a Christian church and then they sit down in the congregation and begin to listen to what is being said from the pulpit ... [and] by the leaders ... [and] in the classes, and they realize that this is not Christian and they get out."
Decker offers his explanation of why such a high percentage of converts leave the church so soon. "They don't tell [the converts] the details about men becoming gods and getting many goddess wives and presiding over their own planets," he shares. "And they leave out the esoteric theology of Mormonism that separates it from Christianity."
The author says even many of the missionaries themselves become disillusioned. "Fifty percent of the Mormons who fulfill their missions leave the church within two years, and 25 percent of them walk off the mission field because they know they're presenting lies," adds Decker.
According to Decker, any growth of Mormonism in the U.S. is from babies being born into the religion by Mormon parents.