"And now, my beloved brethren, and also Jew, and all ye ends of the earth, hearken unto these words and believe in Christ; and if ye believe not in these words believe in Christ. And if ye shall believe in Christ ye will believe in these words, for they are the words of Christ, and he hath given them unto me; and they teach all men that they should do good. And if they are not the words of Christ, judge ye—for Christ will show unto you, with power and great glory, that they are his words, at the last day; and you and I shall stand face to face before his bar; and ye shall know that I have been commanded of him to write these things, notwithstanding my weakness.As we accept the truths of the Book of Mormon we will better understand the doctrines found in the Bible. In addition to verifying the truth of the Bible, the Book of Mormon can clarify its teachings. Over the years of translations and copies of copies, changes were introduced into the Bible - on purpose or inadvertently. Most were inadvertent and could have included simply choosing to translate one word in a particular manner. Even aside from changes, people interpret the Bible in many different ways. Interpretations might be similar but many are significantly different.
And I pray the Father in the name of Christ that many of us, if not all, may be saved in his kingdom at that great and last day. And now, my beloved brethren, all those who are of the house of Israel, and all ye ends of the earth, I speak unto you as the voice of one crying from the dust: Farewell until that great day shall come. And you that will not partake of the goodness of God, and respect the words of the Jews [the Bible, mainly the Old Testament], and also my words [the Book of Mormon], and the words which shall proceed forth out of the mouth of the Lamb of God [contained in the Bible, Book of Mormon, Doctrine & Covenants, and spoken by modern prophets], behold, I bid you an everlasting farewell, for these words shall condemn you at the last day" (2 Nephi 33:10-14).
Some people take the Bible as a completely figurative and spiritual book while others take everything strictly literally. Joseph Smith explained it well: "The Presbyterians were most decided against the Baptists and Methodists, and used all the powers of both reason and sophistry to prove their errors, or, at least, to make the people think they were in error. On the other hand, the Baptists and Methodists in their turn were equally zealous in endeavoring to establish their own tenets and disprove all others....the teachers of religion of the different sects understood the same passages of scripture so differently as to destroy all confidence in settling the question by an appeal to the Bible" (Joseph Smith-History 1:9,12).
Joseph did not state that the Bible was false or untrue or wrong; he just said that people argued and debated over what particular passages of scripture meant. Some of the arguments were and are very bitter. If he asked the Baptists, they said one thing. If he asked the Methodists, they said another. These debates continue today; look at the myriad Christian churches throughout the world. There are as many different and distinct churches as verses in the Bible (to be a bit hyperbolic)! So who has the truth? Do they all have the truth? I believe all have truth but do all have all the truth (or at least all the truths necessary for salvation)? No. How can we know the truth? Who is the source of truth? Who inspired prophets in Biblical times and gave them revelations that they wrote down? The Lord did.
Because God is the source of truth, Joseph's solution was to do as the Bible suggested in James 1:5 (verse 6 is also linked to), "If any of you lack wisdom, let him ask of God, that giveth to all men liberally, and upbraideth not; and it shall be given him." Joseph knew he had to ask the Lord in prayer. The Lord is the source of Truth so Joseph went to that Source. In response to Joseph's prayer at the age of 14, Heavenly Father and Jesus Christ appeared to Joseph. They called him by name and called him to be the prophet, a role he would grow into over the years.
Link to part 3 of this essay.