Satan

Satan, also called the adversary or the devil, is the enemy
of righteousness and those who seek to follow God. He is a
spirit son of God who was once an angel “in authority in the
presence of God” (D&C 76:25; see also Isaiah 14:12; D&C
76:26–27). But in the premortal Council in Heaven, Lucifer, as
Satan was then called, rebelled against Heavenly Father and
the plan of salvation. In this rebellion against God, Satan
“sought to destroy the agency of man” (Moses 4:3). He said:
“I will redeem all mankind, that one soul shall not be lost,
and surely I will do it; wherefore give me thine honor”
(Moses 4:1).
Satan persuaded “a third part of the hosts of heaven” to
turn away from the Father (D&C 29:36). As a result of this
rebellion, Satan and his followers were cut off from God’s
presence and denied the blessing of receiving a physical
body (see Revelation 12:9). They were also denied the opportunity
to receive any inheritance in a kingdom of glory.
Heavenly Father allows Satan and Satan’s followers to
tempt us as part of our experience in mortality (see 2 Nephi
2:11–14; D&C 29:39). Because Satan “seeketh that all men
might be miserable like unto himself” (2 Nephi 2:27), he and
his followers try to lead us away from righteousness. He
directs his most strenuous opposition at the most important
aspects of Heavenly Father’s plan of happiness. For example,
he seeks to discredit the Savior and the priesthood, to cast
doubt on the power of the Atonement, to counterfeit revelation,
to distract us from the truth, and to contradict individual
accountability. He attempts to undermine the family by
confusing gender, promoting sexual relations outside of marriage,
ridiculing marriage, and discouraging childbearing by
married adults who would otherwise raise children in righteousness.
You do not have to give in to Satan’s temptations. You
have the power within you to choose good over evil, and you
can always seek the Lord’s help through prayer. (See
“Temptation,” pages 174–76.)
Additional references: Isaiah 14:12–17; 1 Nephi 15:23–24; 2 Nephi 2:16–18;
Moroni 7:12; D&C 10:5; 29:36–40, 46–47; 76:25–29
See also Agency; Sin; Temptation