Complex sentence: Smith claimed to receive a set of gold plates from an angel named Moroni that contained a record of ancient inhabitants of the Americas, and that he was charged with translating the writing on the plates by the power of God.
Split into simpler sentences: Smith claimed to receive a set of gold plates from an angel named Moroni that contained a record of ancient inhabitants of the Americas. Smith was then charged by the angel with translating the writing on the plates by the power of God.