Complex sentence: The teachings of Yevon--said to have been left by Yevon to his daughter, Lady Yunalesca--were implemented by Bevelle to maintain order through giving the people hope that Spira may someday be free of Sin should they atone for their "sins".
Split into simpler sentences: The teachings of Yevon--said to have been left by Yevon to his daughter, Lady Yunalesca--were implemented by Bevelle to maintain order. They did so by leading Spirans to believe that Spira may someday be free of Sin, should they atone for their "sins".