Original sentence: Most importantly, Mormons believe that the Restoration in question has already happened:  The original church of Jesus Christ, known as the primitive church by historians, is claimed to have been restored by Joseph Smith, the first Prophet of the Church of Jesus Christ of Latter-day Saints
Edited sentence: Most importantly, Mormons believe that the Restoration in question has already happened:  The original church of Jesus Christ, known as the primitive church by historians, is claimed to have been restored by Joseph Smith, the first modern Prophet of the Church of Jesus Christ of Latter-day Saints