Members of the Church of Jesus Christ of Latter-day Saints believe that not one, but three heavens exist. The Celestial Kingdom, the Terrestial Kingdom, and the Telestial Kingdom. The Celestial is the highest, where God and the ones who followed His law all their earthly lives reside. The Terrestrial is the middle, where people who followed the law of Moses reside. The Telestial is the lowest, where the ones who followed carnal law reside. Everyone else is sent to a Spirit Prison, otherwise known as: Hell. There they are taught the Book of Mormon, had they never been given, or they refused the opportunity to do so when they had been alive. After learning all that God has to teach, the people trapped in Hell are then moved either to an Earthly body again, or into the Telestial Kingdom to reside.
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The Book of Mormon is the guide that the Mormon's use to lead them through this lifetime, and into the next.