All gospel truths and all binding testimony must be established in the mouth of two or three witnesses. It is this very principle that demanded the coming forth of the Book of Mormon to sustain and defend the Bible (see 2 Nephi 29:8). Here Nephi indicates to his people that they are obligated to believe in the Redeemer because they have the testimony of three witnesses: himself, his brother Jacob, and Isaiah—all of whom had seen Christ. (See 1 Nephi 12:6; 2 Nephi 2:3-4; Isaiah 6:1.)