First Nephi 10:6

Wherefore, all mankind were in a lost and in a fallen state, and ever would be save they should rely on this Redeemer.

The Book of Mormon is a witness for Jesus Christ. It stands as a companion to the Bible as a second testament to the divine sonship of Jesus and his role as the Redeemer and Savior of the world. Statements like the one in this verse appear all throughout the book. President Ezra Taft Benson taught that the Book of Mormon is the keystone of the Latter-day Saint religion. This is because it teaches powerfully of the Chief Cornerstone, who is Jesus Christ. Just as the Cornerstone was a stumbling block to the Jews in 34 A.D., who were blinded by false expectations of the Messiah in their day, the keystone is a stumbling block to many in 2016 A.D. who are blinded by false expectations that God is silent in our day, He has done His work, left His mark, and now He watches the world grope about in the dim light of the philosophies of men mingled with scripture. To those, however, who are willing to approach God about the truth, the keystone of the Book of Mormon can become a steppingstone to a new understanding that God is not done with us, He still has something to say, He is still making His mark on honest and sincere hearts, and He does not watch us grope in darkness because He has offered us additional light. When we read the Book of Mormon, the light goes on and the darkness flees.