Mormons in the Antebellum Reform Movement
The leader of the Mormons was a young, ambitious, but economically unsuccessful man from upstate NY named Joseph Smith. He believed in radical tactics for an end that would bring people back to "true" Christianity.
Smith claimed to receive "Golden Plates" from angels from heaven in 1820, as evidenced from the video below from the official Mormon YouTube channel. He believed that truth was missing from the many different sects of the Christian religion and claimed that God gave him the authority to act in His name and in the name of His son Jesus Christ. Smith's awakening to his beliefs was also a part of the greater Second Great Awakening.
The "Golden Plates" became known as the Book of Mormon. Smith said that this book was the revival of the true Gospel and the only unbiased account of Jesus Christ and the Genesis of Christianity. He also said that Mormonism was the reawakening of the true Christian faith and those who were concerned, as he had been, that the other sects were wrong about what God wanted should join his church.
Smith was extremely charismatic and used preaching effectively, especially in open forums, and took advantage of living in the "Burned Over District" in upstate NY to spread his word. It worked, and he gained many followers and became very successful. There are now 15 million members of the Mormon church in the world. However, his failures came with his belief in polygamy and his discount of the Holy Trinity, causing him to be considered radical. He also was ostracized for his abolitionist sympathies, particularly in Missouri, a slave state, and his discount of all other versions of Christianity.
Smith's radical ideas made him unpopular with his neighbors. He wanted to establish a permanent "New Jerusalem" in Jackson County, Missouri, but was expelled in 1833 by disgruntled neighbors who believed what he was saying was heretical and that he was intruding on their land. They met him and his followers with violence. The Mormons then moved to Illinois. There, Smith met his demise in 1844 after he had been arrested, when an angry mob forced him out of jail and shot and killed him. His followers then followed Brigham Young on an epic trek across the country where they finally established a permanent residence in Salt Lake City, Utah.