A keystone keeps an arch in place; without a keystone the whole arch will collapse. Why is the Book of Mormon the keystone of our religion? Because it is central to our history and theology. It is the text for this dispensation. Nothing took priority over getting the Book of Mormon translated and published. Everything was held until that was accomplished. There were no Apostles until it came into being. Ten days after the book’s publication the Church was organized. Publication of the Book of Mormon preceded missionary work because Samuel Smith needed to have it in hand before he could go forward as the first missionary of the Church. Sections 17 and 20 of the Doctrine and Covenants indicate that the Brethren could not fully know the divinity of the latter-day work until the Book of Mormon was translated.
As a young missionary I personally learned the importance of the prophetic mission of Joseph Smith and the Book of Mormon in missionary work. Elder Wm. Grant Bangerter, Elder Lynn A. Sorensen, and I, along with other dedicated young men, were pioneer missionaries in Brazil half a century ago. One year we converted only three people. In 1994 in this same country 43,247 souls were converted. There are now more than one hundred stakes of Zion in Brazil. There are seven stakes in the city where Elder Bangerter and I, laboring as companions, found the first members of the Church.
What is the difference between then and now? Why was it so hard in the beginning and so fruitful now? In large measure it was because the only scripture we had was the Bible. The only expression concerning the Book of Mormon came from our own testimonies spoken in a strange tongue. Unlike Samuel Smith, we did not have the Book of Mormon in hand to leave with any who might be interested. Only after the Book of Mormon was published in Portuguese did the great harvest of converts come. The Lord has made clear that this generation shall remain under condemnation “until they repent and remember the new covenant, even the Book of Mormon” (D&C 84:57). (“Joseph Smith and the Book of Mormon,” Ensign, Jan. 1996)