Q. How come the Mormons put the Book of Mormon, the Doctrine and Covenants, and the Pearl of Great Price up there with the Bible?
A. Without a Book of Mormon, of course, there'd be no Church of Jesus Christ of Latter-day Saints, so there's a solid claim for divine inspiration right off.
LDS founder Joseph Smith testified that in 1823 he'd been guided to gold tablets which told the story of the migration of some ancient Israelites to North America. Later, according to Smith's account, the resurrected Christ visited that transplanted tribe. The Book of Mormon, as Smith's testament was called, was named, not surprisingly, for a certain prophet Mormon who was credited with producing the tablets to begin with.
Smith's writings didn't stop there. He reported further divine revelations. One collection became the Doctrine and Covenants, which spells out how church members should behave, what kind of government they should have, rules of good health and warnings against using alcohol or caffeinated drinks.
The Pearl of Great Price became the third great building block, a collection that Smith said were translations of further truths made known to him by God. Two were represented as ancient documents about two pillars of Christianity and Judaism, Abraham and Moses. Another section was Smith's own account of his encounters with the divine realm.
All of these books were sacred works along with the Christian Bible. They define the essential Mormonism.
Mormons saw these new revelations as continuations of Christian and Jewish Scriptures, not replacements for them. With them, they built a religion that is probably more American in origin than any other, mingling the verities of the Holy Land with North American roots.