I’m not sure if that passage is in there, I have zero interest in reading poorly written fiction, but it is a teaching of the LDS. Here are some statements made by various leaders and scholars of the LDS.
> The Mormon scriptures state: “this church [Joseph Smith’s]… only true and living church upon the face of the whole earth” (Doctrine and Covenants, 1:30).
> Apostle Bruce McConkie states: “There is no salvation outside The Church of Jesus Christ of Latter-day Saints” (Mormon Doctrine, p.670).
> Marion Romney (speaking as a member of the LDS First Presidency) said, “This Church is the ensign on the mountain spoken of by the Old Testament prophets. It is the way, the truth, and the life” (Conference Report, April, 1961, pg. 119).
> Mormon president and prophet Brigham Young declared: “he that confesseth not that Jesus has come in the flesh and sent Joseph Smith with the fullness of the Gospel to this generation, is not of God, but is anti-christ” (Journal of Discourses, vol.9, p.312).
> Mormon president and prophet Ezra Taft Benson stated: “This is not just another Church. This is not just one of a family of Christian churches. This is THE Church and kingdom of God, THE only true Church upon the face of the earth…” (Teachings of Ezra Taft Benson, p.164-165).
> What is more, Mormon leaders have taught that Joseph Smith must give his consent before anyone can enter heaven:
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> [There is] “no salvation without accepting Joseph Smith” (Joseph Fielding Smith, in Doctrines of Salvation, vol. 1, p.190).
> “No man or woman in this dispensation will ever enter into the celestial kingdom of God without the consent of Joseph Smith” (Brigham Young, in Journal of Discourses, vol. 7, p.289).
> Bruce McConkie states: “If it had not been for Joseph Smith and the restoration, there would be no salvation” (Mormon Doctrine, p.670).
> Joseph Fielding Smith said: “If Joseph Smith was verily a prophet, and if he told the truth…no man can reject that testimony without incurring the most dreadful consequences, for he cannot enter the kingdom of God” (Doctrines of Salvation, vol. 1, p.190).
> Brigham Young stated: “every man and woman must have the certificate of Joseph Smith, junior, as a passport to their entrance into the mansion where God and Christ are” (Journal of Discourses, vol. 7, p.289).
> George Q. Cannon: “If we get our salvation, we shall have to pass by him [Joseph Smith]; if we enter our glory, it will be through the authority he has received. We cannot get around him [Joseph Smith]” (quoted in the Melchizedek Priesthood Study Guide, p. 142, 1988).