"In case (you're) wondering if this group of Christians is some kind of cult, they are not," he wrote in the letter dated April 5, 1984. "I thought about that a lot at first, too. But God has shown me that they are truly his disciples. God has shown me through Scripture."
The Holy Bible. Old Testament. New Testament. The Gospels.
Through the ages, their chapters and verses have been used to defend slavery, and to abolish it.
To embrace capital punishment, and to denounce it.
To convince followers that the path they are on is the one and only way to salvation.
So it is with alternative religious movements. While some use more of the Bible than others, many invoke at least enough Scripture to evoke a sense of godly approval.
Church Universal and Triumphant founder Elizabeth Clare Prophet, for example, quotes liberally from the Bible to bolster her argument that reincarnation was part of Jesus' message. Aquarian Concepts Community cites the New Testament over and over to encourage trust in its divine administration at Planetary Headquarters.
And for the Brothers and Sisters, a nomadic band of Christians who travel quietly across the country in search of recruits, the Bible isn't just a part of its message -- it is the focus of their entire faith. As Kraig Foster put it 13 years ago: "God has shown me through Scripture."
The Brothers and Sisters select strong excerpts for their recruits, which, taken literally and without regard to context, certainly appear clear enough: leave straightaway, forsake all, take up your cross daily.
But just how accurate are their interpretations? The San Diego Union-Tribune took some of the group's most-emphasized verses to local Bible experts to help separate the wheat from the chaff, scripturally speaking.
First, there is the story of the rich man in the 10th chapter of Mark. The Brothers and Sisters use this voraciously to persuade recruits that if they are serious about eternal life, they must give up their jobs, their education and their wordly goods.
"It's a misuse of the text to just lift it out," cautions Florence Gillman, a biblical studies scholar at the University of San Diego.
To emphasize her point, Gillman flips over to Luke 19 and the story of another wealthy man, named Zacchaeus, who gives away only half his goods to the poor and still wins praise from Jesus.
"You can't generalize," she says, looking up from her Bible in a coffee shop on the campus of the Roman Catholic university.
Mark Strauss, at Bethel Theological Seminary, agrees.
"What Jesus is saying (in Mark) is that this individual had one thing that was holding him back, his attachment to his material goods," says Strauss, a New Testament expert who teaches at the San Diego campus of the Protestant seminary.
"This is specific advice to this one man. Others might not be held back by material goods. There are multiple examples where individuals do not sell all their possessions, but are still considered holy and held in good regard in the Bible."
The Brothers and Sisters also are strong on separation from family, using verse after verse to convince recruits that they must cut their ties.
But as Strauss, Gillman and others point out, there are many verses with quite opposite messages: One of the Ten Commandments deals specifically with honoring mothers and fathers; Jesus goes to Peter's home and heals his mother-in-law, suggesting strongly that Peter did not abandon his family; the apostle Paul refers to husbands traveling with their wives in ministry; the evangelist Philip had a home with four daughters.
And in the Gospel of John, some of Jesus' final words from the cross were to his mother standing nearby.
The bottom line is context and discernment, say the scholars. Read the Bible as a whole message and determine what it means for your life.
The Brothers and Sisters use only the King James Version, a 17th century translation that continues to be a sentimental favorite among some segments of Christianity despite newer, and arguably more comprehensive, versions. But there may be another reason that leader Jim Roberts insists on the King James Version.
"It is harder to understand, so you need an authority to interpret it," says Strauss.
There is a measure of genuine Christianity in the Brothers' and Sisters' use of Bible verses, Gillman notes. But, she adds, the selected texts are bound together "in a cultic straitjacket."
"Real Christianity is peaceful, happy to shout from the housetops," she says. "It has no secrets."