Satan, called Lucifer before his fall, was an angel who fell from heaven and became a devil, having sought that which was evil before God (2 Nephi 2:17). The record applies to him Isaiah’s taunt, “How art thou fallen from heaven, O Lucifer, son of the morning!” (2 Nephi 24:12), and a later revelation identifies him as an angel “who was in authority in the presence of God” who rebelled against the Only Begotten and was thrust down, thereafter called Perdition (Doctrine and Covenants 76:25-27). Having become miserable forever, he sought the misery of all mankind, beguiling Eve as “that old serpent… the father of all lies,” and seeks “that all men might be miserable like unto himself” (2 Nephi 2:18, 27).
He is named the author of all sin and the source of the secret oaths and combinations handed from generation to generation: the same being who plotted with Cain, prompted the tower, and put the works of darkness into the heart of Gadianton (Helaman 6:26-30). His methods range from stirring people to anger against good, to lulling them into carnal security with “All is well in Zion,” to telling them there is no hell and no devil (2 Nephi 28:20-27). A distinct and more dangerous mode of his deception is counterfeit holiness: Jacob teaches that he “transformeth himself nigh unto an angel of light,” and Korihor later confessed that it was precisely in this guise—as an angel—that the devil came to him and taught him what to say (2 Nephi 9:9; Alma 30:53).
His power over the human heart rises and falls with the people’s wickedness. Where the people dwell in righteousness he has no power and cannot be loosed; transgressors, by contrast, are delivered up to him to be sifted “as chaff before the wind” (1 Nephi 22:26; Alma 37:15).
The record states that Satan will at length have no power over the hearts of men, that he cannot be loosed while the people are righteous, and that he will be bound a thousand years and cast into the bottomless pit (1 Nephi 22:15, 26; Revelation 20:1-3).
Against his temptations the record prescribes continual watchfulness and prayer, laying hold on the word of God, which divides asunder “the cunning and the snares and the wiles of the devil” (Alma 34:39; Helaman 3:29; 3 Nephi 18:15, 18; Mosiah 4:30). Men are left free to choose liberty and eternal life through the Mediator, or captivity and death under the power of the devil (2 Nephi 2:27).