Which explains a lot.
According to CNN.com:
Beck's emerging role as a national leader for Christian conservatives is surprising not only because he has until recently stressed a libertarian ideology that is sometimes at odds with so-called family values conservatism, but also because Beck is a Mormon.
Many of the evangelicals who Beck is speaking to and organizing, including [Rev. Richard] Land [of the Southern Baptist Convention], don't believe he is a Christian. Mormons, who are members of the Church of Jesus Christ of Latter-day Saints, call themselves Christian.
"There's a long history of tensions between Mormons and evangelicals and some of that is flat-out theology," says John C. Green, an expert on religion and politics at the University of Akron. "Mormons have additional sacred texts (to the Bible) and a different conception of God."
"It's also competitive," Green said, "because evangelicals and Mormons are both proselytizing in the U.S. and around the world."