The Book of Moses is part of the Mormon scripture known as The Pearl of Great Price (1). It was published just prior to 1850 in church newspapers, and was officially canonized in 1880 by the Mormon church.
Mormons believe that the Book of Moses was Joseph Smith’s inspired translation of selections from the writings of the actual historical Moses while he working on his revision of the King James Version of the Bible. They believe that God revealed the writings of Moses to Joseph Smith, and that it can therefore be considered inspired scripture.
In its totality the Book of Moses has eight chapters all of which include significant changes from the original Book of Genesis as it is found within the Hebrew Bible. Smith added numerous stories to the Genesis narratives which include, but are not limited to, adding 15 verses to the beginning of the Genesis account, an alleged vision that Moses had and recorded, a story about Moses and his temptation by Satan, a story about Lucifer before he was cast out of heaven, additional details concerning Adam and Eve, the Fall and its effects on mankind, the story of Cain and Abel (and Cain’s murder of Abel), the ministry of Enoch, the establishment of Zion in Enoch’s day and his visions of God, and events leading up to the story of the Flood in Genesis including the idea that Noah shared the gospel of Jesus Christ, and that because people rejected this message, God decreed that he would destroy all flesh by a flood.
Mormons derive many teachings from this work, and they strongly believe that by studying it people will learn the true doctrines of the Creation, the Fall, and the Atonement of Jesus Christ. For instance, it informs the Mormon belief that God created all things spiritually prior to creation, and that Jesus Christ was known by name to Old Testament Prophets. It also provides teachings on how to resist temptation and how temptation works, a truth primarily taught in the story of Satan’s attempt to get Moses to worship him just after Moses had a vision of God. Moses spurns Satan’s attempts by asserting his personal identity as a son of God (2).
None of these stories, many of which pave the foundation for Mormon doctrine, are themselves found in the Book of Genesis, and Mormons claim that such details were revealed supernaturally to Smith and therefore they should be believed.
1. The Church of Jesus Christ of Latter Day Saints. Introduction to the Book of Moses: Teacher Manuel. Available.
2. The Church of Jesus Christ of Latter Day Saints. Introduction to the Book of Moses: Teacher Manuel: Lesson 6. Available.