For other senses of the word "agency", see
agency.Agency (also referred to as free agency or moral agency), in
Latter-day Saint theology, is "the privilege of choice which was introduced by God the Eternal Father to all of his spirit children in the premortal state". Mortal life is viewed as a test of faith, where our choices are central to the
Plan of Salvation. "It was essential for their eternal progression that they be subjected to the influences of both good and evil". Mormons believe that Lucifer presented an alternative plan, which resulted in a war in heaven, with Lucifer being cast out of heaven and becoming Satan.
See more at Wikipedia.org...