Subtitled Another Testament of Jesus Christ, “The Book of Mormon is another witness of Jesus Christ and confirms the truths found in the Holy Bible.” (Gospel Topics: Book of Mormon, lds.org)
Mormonism teaches that the Book of Mormon supports and even supplants the Bible as a source of truth. “I told the brethren that The Book of Mormon was the most correct of any book on earth, ..and a man would get nearer to God by abiding by its precepts, than by any other book.” (Joseph Smith, Introduction to the Book of Mormon)
“The Book of Mormon is another witness for the truths taught in the Bible. It also restores ‘plain and precious’ truths that have been lost from the Bible through errors in translation or ‘taken away’ in attempts to ‘pervert the right ways of the Lord.'” (True to the Faith, p. 157-8)
Mormonism teaches that The Book of Mormon was inscribed on golden plates and delivered to Joseph Smith by the angel, Moroni. It contains the story of groups of Jews migrating to the Americas and their subsequent history. This includes a visit from the resurrected Christ. Non-Mormons are encouraged to read The Book for Mormon and prayerfully ask Heavenly Father if the book is true. Surprisingly, very little LDS doctrine is in this book.
Biblical Christianity teaches:
The Bible goes to great length to warn about false teachings that claim to be Christian. (2 Cor. 11:13) By testing and comparing its teachings to the Bible, the Book of Mormon falls under the biblical definition of false teaching.