The Millennium will be ushered in by power (Revelation 20:1–3; D&C 19:1–3; 84:118–19) but maintained by righteousness (see also 1 Nephi 22:26). Satan will be bound and become powerless by the power of God as well as by the righteousness of the Saints. Satan’s followers will be consumed by fire, and the righteous will be preserved by fire. The fire, which can destroy or save, is the glory of the Lord (Helaman 5:23–50; 3 Nephi 25:1).
The Prophet Joseph Smith taught that the devil has no power over individuals in any age, only as they allow him to. 61 But we also realize that while the Lord’s assurance that he will not allow the wicked to destroy the righteous may be true in an ultimate sense or regarding a whole righteous people, there are reasons why he does permit some righteous individuals to be killed (see commentary at Alma 14:6–11).