The concept of spiritual death has varying meanings in various uses and contexts. "Spiritually dead" person may mean someone who is not spiritual (materialist, atheist) - one, who identifies himself with dead matter, though he is a living conscious being. Thus first meaning for "spiritual death" is "to become atheist". Another, narrow, "purified" meaning of "spiritual death" is "death in a spiritual way", "to die being a spiritual person, not being an atheist". Thus this means that "spiritual death" relates to two egos: soul (real self, which is eternal), and ego (false self, which is temporary or material). Difference in meanings come from misidentification of eternal soul to be "spiritually dead" or "material", which is nonsense for theist. For theist there is no such thing as "spiritual death". Matter can be only dead, and soul can only be eternal. As put by the LDS Church, "the body is as a glove, and the spirit the hand that moves". One cannot say "dead life", or "alive death". For contrast you can guess what is the meaning of "material life: life is always spiritual, though "material life" would mean just "to live having materialistic values".
Followers of Ascended Master movements such as the Theosophical Society, I AM Foundation, and Elizabeth Clare Prophet have a different definition of the second death: The final extinguishing of the identity of a soul deemed by God to be beyond redemption. In this theology, people are believed to continue to reincarnate for many lifetimes on Earth with one of two final outcomes: 1) Reunion with God in the ritual of the Ascension, like Jesus, or 2) Final judgment at the "court of the sacred fire," where the soul would be destroyed forever. The Unification Church teaches that spiritual death is the state of separation from God, but that it is not ever irreversible. Spiritual death (death for spiritual person, not for atheist) is the art of learning to die. It is only through this art that the consciousness of death of oneself (the self or ego that is afraid to die) is transformed into consciousness of the eternally new or young self or soul (the self or soul that accepts death for body, but never for soul him/herself, as soul is eternal).
Dr. John B. Calhoun saw the social breakdown of a population of mice given ample resources as a second death. He saw this as a metaphor for the potential fate of man in an overcrowded but resource rich environment and made reference to the second death of the Book of Revelation. Conservative Christian writers, such as Bill Perkins, have echoed this warning.
In his famous anti-war address "Beyond Vietnam: A Time to Break Silence," delivered 4 April 1967 at a meeting of Clergy and Laity Concerned at Riverside Church in New York City, Dr. Martin Luther King, Jr. observed that "[a] nation that continues year after year to spend more money on military defense than on programs of social uplift is approaching spiritual death."
- See Boyd K. Packer, Teach Ye Diligently [Salt Lake City: Deseret Book Co., 1975], pp. 231–33.)
- Buddhadasa Bhikkhu, "Happiness and Hunger", 1986
- John B. Calhoun, "Death Squared: The Explosive Growth and Demise of a Mouse Population" Proc. roy. Soc. Med. Volume 66 January 1973, pp80-88
- Bill Perkins, “Six Battles Every Man Must Win”, Tyndale Press, 1993, p 10