Separation from God and His influences; to die as to things pertaining to righteousness. Lucifer and a third part of the hosts of heaven suffered a spiritual death when they were cast out of heaven (D&C 29:36–37).
Spiritual death was introduced into the world by the Fall of Adam (Moses 6:48). Mortals with evil thoughts, words, and works are spiritually dead while still alive on earth (1 Tim. 5:6). Through the Atonement of Jesus Christ and by obedience to the principles and ordinances of the gospel, men and women can become clean from sin and overcome spiritual death.
Spiritual death also occurs following the death of the mortal body. Both resurrected beings and the devil and his angels will be judged. Those who have willfully rebelled against the light and truth of the gospel will suffer spiritual death. This death is often called the second death (Alma 12:16; Hel. 14:16–19; D&C 76:36–38).