In the Pre-Mortal Life before the creation of the earth, Lucifer, or Satan, rebelled against God. There was a War in Heaven, and Satan was cast out of heaven with all of his followers, one-third of the spirits who dwelt there. Satan and his minions were cast down to earth. Satan and his followers will ever be spirits; they never will be able to attain bodies, will never be able to dwell on earth as physical beings, nor will they be resurrected.
- In the beginning, when a powerful spirit was cast down for rebellion, “he became Satan, … the devil, the father of all lies, to deceive and to blind men, and to lead them captive at his will” (Moses 4:4). He and the spirits who follow him are still deceiving the world. Modern revelation declares that “Satan hath sought to deceive you, that he might overthrow you” (see Doctrine and Covenants 50:2–3). Satan’s methods of deception are enticing: music, movies and other media, and the glitter of a good time. When Satan’s lies succeed in deceiving us, we become vulnerable to his power.
The mission of Satan and his spirit-followers is to make war with the Saints and to destroy the souls of all men (Revelation 12).  Evil spirits have the power to tempt men, to entice them into wicked behavior, to lead them away from the gospel, and even to possess the bodies of men.
- Revelations come to men just as easily from devils as they do from holy sources. By rebellion and wickedness men may commune with evil spirits, whereas by obedience and righteousness they might have seen angels and had the communion of the Holy Spirit. All these things are governed by law. 
One way evil spirits are able to overcome the righteous is to lull them into "carnal security."
- The prophet Nephi warns...: “And others will he pacify, and lull them away into carnal security, that they will say: All is well in Zion; yea, Zion prospereth, all is well—and thus the devil cheateth their souls, and leadeth them away carefully down to hell” (2 Nephi 28:21).
- Those who fall for this deception may profess to believe in God, but they do not take His commandments or His justice seriously. They are confident in their own prosperity and conclude that God must have accepted their chosen route.
- “Yea, and there shall be many which shall say: Eat, drink, and be merry, for tomorrow we die; and it shall be well with us.
- “And there shall also be many which shall say: Eat, drink, and be merry; nevertheless, fear God—he will justify in committing a little sin; … there is no harm in this; and do all these things, for tomorrow we die; and if it so be that we are guilty, God will beat us with a few stripes, and at last we shall be saved in the kingdom of God” (2 Nephi 28:7–8). 
As men are seduced by evil spirits, society is affected, and insensitivity to the promptings of the Lord causes men to become "lovers of their own selves, … disobedient to parents, unthankful, unholy, without natural affection, … despisers of those that are good, … lovers of pleasures more than lovers of God” (2 Timothy 3:1–4). “Evil men and seducers shall wax worse and worse, deceiving, and being deceived” (2 Timothy 3:13).
However, Satan only has influence over men, if they invite him, or allow him to exert power. Said the Prophet Joseph Smith:
- Satan cannot seduce us by his enticements unless we in our hearts consent and yield. Our organization is such that we can resist the devil; if we were not organized so, we would not be free agents.” 
- “The devil has no power over us only as we permit him; the moment we revolt at anything which comes from God, the devil takes power.” 
On May 16, 1841, the Prophet addressed the Saints: “President Joseph Smith … observed that Satan was generally blamed for the evils which we did, but if he was the cause of all our wickedness, men could not be condemned. The devil could not compel mankind to do evil; all was voluntary. Those who resisted the Spirit of God, would be liable to be led into temptation, and then the association of heaven would be withdrawn from those who refused to be made partakers of such great glory. God would not exert any compulsory means, and the devil could not; and such ideas as were entertained [on these subjects] by many were absurd.” 
In the Doctrine and Covenants, section 46, verse 7, we read,
- Ye are commanded in all things to ask of God, who giveth liberally; and that which the Spirit testifies unto you even so I would that ye should do in all holiness of heart, walking uprightly before me, considering the end of your salvation, doing all things with prayer and thanksgiving, that ye may not be seduced by evil spirits, or doctrines of devils, or the commandments of men; for some are of men, and others of devils.
- Bruce R. McConkie, Gospel Doctrine, Second Edition, p. 246.
- Dallin H. Oaks, “Be Not Deceived,” Ensign, Nov 2004, 43. 
- Quoted by William P. McIntire, reporting a discourse given by Joseph Smith in early 1841 in Nauvoo, Illinois; William Patterson McIntire, Notebook 1840–45, Church Archives.
- Quoted by William Clayton, reporting an undated discourse given by Joseph Smith in Nauvoo, Illinois; in L. John Nuttall, “Extracts from William Clayton’s Private Book,” p. 8, Journals of L. John Nuttall, 1857–1904, L. Tom Perry Special Collections, Brigham Young University, Provo, Utah; copy in Church Archives.
- History of the Church, 4:358; bracketed words in original; paragraph divisions altered; from a discourse given by Joseph Smith on May 16, 1841, in Nauvoo, Illinois; reported by Times and Seasons, June 1, 1841, p. 429.