I'll address other ways the Book of Mormon can help clarify the Bible. For instance, there are many differences in beliefs about the resurrection. Some people believe we will remain as spirit bodies. Others believe we will have physical bodies. Some believe that all will be resurrected while others believe only some will be resurrected. The Book of Mormon teaches that we will all be resurrected - all who ever lived on the earth - and that it is a physical resurrection (see Alma 40; Mosiah 15). Having these two witnesses (we also have additional teachings by modern prophets - see D&C 76, for example) clarifies doctrine. We no longer have to rely solely on the Bible, even as wonderful as it is. We can understand the doctrines with more clarity and purity. However, it is the living prophets who provide true clarity and additional light and knowledge. [image by AllAboutMormons.com].
Without living prophets and even with the Book of Mormon, the doctrines of the gospel would quickly corrupt (we certainly have a broad range of opinions about many doctrines or practices within the Church, even among the General Authorities), just as they did following the Savior's resurrection and the deaths of His original apostles. It's not the books that the most important - what's most important is the gift of the Holy Ghost - the ability to receive personal witnesses and revelation concerning the truths of the gospel - and the Priesthood power and authority. The priesthood allows for the organization of the church to function and exist. The priesthood keys as held by the prophet (and given to others through delegation and inspired callings) allow the ordinances of the gospel to be performed here on earth and be notarized in heaven.
As members of The Church of Jesus Christ of Latter-day Saints, we claim that the Bible is the word of God. We do not, however, accept it as a closed canon. We view scripture as open, expanding, and contemporary through ongoing revelation. We believe this view to be Biblical. Just as what Amos wrote added to what Moses had written (to refer back to Elder Holland's quote at the beginning of this essay) and what Paul wrote added to the words of the Redeemer, we claim that modern prophets give new scripture. Instead of simply retranslating the Bible into more modern English, we have prophets who receive new revelation. We certainly can apply the doctrines and teachings of the Bible to our day and adapt them to our understanding and lives but we are not limited any more to the Bible. Does God love His children today any less than those who lived during Biblical times? No! He speaks to prophets today just as He did then. He caused the Book of Mormon to speak from the dust (see Isaiah 29:4; 2 Nephi 26:16; 2 Ne. 33:13). He restored His Church through the prophet Joseph Smith, a restoration that brought about the blessings and promises of the fullness of the gospel, including the blessings of continuing revelation to prophets who speak with authority from God. God speaks to us today - individually (just as He has done throughout the ages) and through prophets. Not only does the Book of Mormon stand as Another Witness of Jesus Christ, but also the testimonies of the prophets verify the truth of the Bible and the divinity of our Lord Jesus Christ, the Atoner.
Link to part 4 of this essay.