President Brigham Young taught that the postmortal spirit world is on the earth, around us (see Teachings of Presidents of the Church: Brigham Young , 279).
Spirit beings have the same bodily form as mortals except that the spirit body is in perfect form (see Ether 3:16). Spirits carry with them from earth their attitudes of devotion or antagonism toward things of righteousness (see Alma 34:34). They have the same appetites and desires that they had when they lived on earth. All spirits are in adult form. They were adults before their mortal existence, and they are in adult form after death, even if they die as infants or children (see Teachings of Presidents of the Church: Joseph F. Smith , 131–32).
The prophet Alma in the Book of Mormon taught about two divisions or states in the spirit world.
Paradise. According to the prophet Alma, the righteous spirits rest from earthly care and sorrow. Nevertheless, they are occupied in doing the work of the Lord. President Joseph F. Smith saw in a vision that immediately after Jesus Christ was crucified, He visited the righteous in the spirit world. He appointed messengers, gave them power and authority, and commissioned them to “carry the light of the gospel to them that were in darkness, even to all the spirits of men” (D&C 138:30).
The Church is organized in the spirit world, and priesthood holders continue their responsibilities there (see D&C 138:30). President Wilford Woodruff taught: “The same Priesthood exists on the other side of the veil. … Every Apostle, every Seventy, every Elder, etc., who has died in the faith as soon as he passes to the other side of the veil, enters into the work of the ministry” (Deseret News, Jan. 25, 1882, 818).
Family relationships are also important. President Jedediah M. Grant, a counselor to Brigham Young, saw the spirit world and described to Heber C. Kimball the organization that exists there:
“He said that the people he there saw were organized in family capacities. … He said, ‘When I looked at families, there was a deficiency in some, … for I saw families that would not be permitted to come and dwell together, because they had not honored their calling here’” (Deseret News, Dec. 10, 1856, 316–17).
Spirit Prison. The Apostle Peter referred to the postmortal spirit world as a prison, which it is for some (see 1 Peter 3:18–20). In the spirit prison are the spirits of those who have not yet received the gospel of Jesus Christ. These spirits have agency and may be enticed by both good and evil. The spirits may progress as they learn gospel principles and live in accordance with them. The spirits in paradise can teach the spirits in prison (see D&C 138). If they accept the gospel and the ordinances performed for them in the temples, they may leave the spirit prison and dwell in paradise.
Also in the spirit prison are those who rejected the gospel after it was preached to them either on earth or in the spirit prison. These spirits suffer in a condition known as hell. They have removed themselves from the mercy of Jesus Christ, who said, “Behold, I, God, have suffered these things for all, that they might not suffer if they would repent; but if they would not repent they must suffer even as I; which suffering caused myself, even God, the greatest of all, to tremble because of pain, and to bleed at every pore, and to suffer both body and spirit” (D&C 19:16–18). After suffering for their sins, they will be allowed, through the Atonement of Jesus Christ, to inherit the lowest degree of glory, which is the Telestial kingdom.