A straightforward reading of the Book of Mormon appears to endorse eternal punishment in hell for many people. A random example of this is found in 2 Nephi 28.15:
O the wise, and the learned, and the rich, that are puffed up in the pride of their hearts, and all those who preach false doctrines, and all those who commit whoredoms, and pervert the right way of the Lord, wo, wo, wo be unto them, saith the Lord God Almighty, for they shall be thrust down to hell!
Passages like that from the Book of Mormon (BOM) could be multiplied, but you get the picture. Now, if the BOM was allowed to stand alone as a text and govern the LDS church, things would look very different. But in essence, the book simply establishes the authority of Joseph Smith: “for the thing, which the Lord shall bring forth by his hand, by the power of the Lord shall bring my people unto salvation” (2 Nephi 3.15). Once Smith was established in his role of authority by the book he produced, he started improvising new theological viewpoints almost immediately.
In fact, a vision given to the false prophet in March, 1830 said that “Endless” is one of God’s names, therefore ‘endless’ punishment simply means ‘God’s punishment’ or punishment from God (Doctrine and Covenants 19). Mormon doctrine developed away from the Book of Mormon on many points and, by extension, away from the Bible. Mormon Professor James McLachlan writes:
With respect to life after death, the LDS church is a universalist religion. All beings have immortality through the atonement of Christ. Joseph Smith claimed that not only humans but animals and plants have eternal spirits (Moses 3:5, 19; 7:48-49; Abraham 3:18-19). Every creature is immortal, having everlasting life, but “eternal life” is interpreted as deification…all will attain immortality, but only those who learn to love perfectly will attain godhood, eternal life” (Musser and Paulsen, 2007).
Essentially almost everyone is ‘safe’ in the Mormon scheme of things – we’ll all end up in one of the three kingdoms. Craig Hazen has summarized things accurately:
Everyone in the next life (except for the small handful of “sons of perdition”) would ultimately enter (perhaps after a limited time in a purgatorial setting) one of the “three degrees of glory” of which even the lowest level (the telestial) has a glory that “surpasses all understanding” (D&C 76:89). [this revelation]…provided the answer to another important question that was probably being asked by early seekers: Why must I join the church if in the end all are going to be saved anyway? Answer: to have a shot at the highest state of glory” (Beckwith, Mosser, Owen 2002).
There is only one category of people in the LDS scheme of things that are in trouble: the sons of perdition. Who are the sons of perdition? Basically they are apostate Mormons:
“Those in this life who gain a perfect knowledge of the divinity of the gospel cause, a knowledge that comes only by revelation from the Holy Ghost, and who then link themselves with Lucifer and come out in open rebellion, also become sons of perdition” (McConkie 1966).
The bottom line seems to be that you are better off living any way you choose than in joining the LDS church and then leaving it. All of mankind will experience some sort of enjoyable eternal life with the exception of those who betray the LDS church.