Mormons teach that during the three days between Jesus' burial and resurrection, he visited the spirit-world and ministered to the righteous Latter-day Saints dwelling in paradise. Dr. Robert Millet writes:
Between the time of Christ's death on the cross and his rise from the tomb, he went into the postmortal spirit world, preached his gospel, organized the faithful, in order that the message of truth might be made available to all who are willing to receive it.
Mormons base their teaching on this Bible passage:
For Christ also suffered once for sins, the righteous for the unrighteous, that he might bring us to God, being put to death in the flesh but made alive in the spirit, in which he went and proclaimed to the spirits in prison, because they formerly did not obey, when God's patience waited in the days of Noah, while the ark was being prepared, in which a few, that is, eight persons, were brought safely through water (1 Peter 3:18-20).
This passage has had many interpretations, but perhaps the best one is presented by Dr. Craig Blomberg, rejecting the suggestion that Jesus offered salvation to dead humans or spirits in prison:
This passage describes Christ's announcement of victory over the demonic world (so directly involved in that particularly wicked era just prior to the flood, 2 Peter 2:4) than any postmortem offer of repentance to the unevangelized.
According to LDS teaching, before Jesus' ministry in paradise, those suffering God's wrath in spirit-prison were unable to repent, accept the LDS plan of salvation, and cross over into the realm of Mormon paradise. After Jesus' ministry in paradise, however, those dwelling in spirit-prison are now given an opportunity to repent, accept the LDS plan of salvation and ordinances, and enter Mormon paradise.
Paradise's Mormon Missionaries
Latter-day Saints believe that when Jesus supposedly visited paradise during his three days in the grave, he commissioned paradise Mormons to become missionaries to those suffering in spirit-prison. The Encyclopedia of Mormonism explains Jesus' visit this way:
He organized the righteous forces and appointed messengers, clothed with power and authority, and commissioned them to go forth and carry the light of the gospel to them that were in darkness (prison-hell).
This missionary work in spirit-prison by paradise Mormons is what the Latter-day Saints say is meant by 1 Peter 4:6: "For this is why the gospel was preached even to those who are dead, that though judged in the flesh the way people are, they might live in the spirit the way God does." In fact, Mormonism believes that the most magnificent and extensive missionary program is taking place in the spirit-world right now, as President Brigham Young concludes:
Compare those inhabitants on the earth who have heard the Gospel in our day, with the millions who have never heard it, or had the keys of salvation presented to them, and you will conclude at once as I do, that there is an almighty work to perform in the spirit world.
Mormon Salvation in Spirit-Prison
As stated above, the Latter-day Saints teach an elaborate salvation scheme that provides a second chance for those dwelling in spirit-prison to convert and become faithful Mormons. Joseph Smith emphasized that it is "no more incredible that God should save the dead, than that he should raise the dead." This is a very central and complex doctrine in Mormonism. This LDS teaching is presented in very broad generalities, however, and many specifics are often lacking and not clarified.
Becoming a Mormon in Spirit-Prison
According to Mormonism, if the spirits dwelling in spirit-prison respond to the preaching of the Mormon missionaries, repent, and put their faith in the salvation plan of the Latter-day Saints, they will have an opportunity to leave spirit-prison and join the righteous Mormons living in beautiful paradise. But this permanent move from spirit-prison to paradise is not automatic. Under the LDS doctrine of salvation for the dead, the spirits that convert to Mormonism in spirit-prison can transfer to paradise only after worthy Mormons on earth have performed required temple ordinances on their behalf and in their name.
The Second-Chance Confusion of Mormonism
There seems to be some confusion, even among some Mormons, about what this second-chance salvation for the dead really means and actually entails, especially as it relates to entering the Celestial kingdom.
In authoritative Mormon teaching, a person who properly understood and rejected Mormonism during his or her earthly life will never have a second opportunity to enter the Celestial kingdom, even if the person repents of his or her sins and receives all the required proxy temple ordinances. Bruce Mc- Conkie is precise on this doctrinal fact:
There is no such thing as a second chance to gain salvation by accepting the gospel in the spirit world after spurning, declining, or refusing to accept it in this life. It is true that there may be a second chance to hear and accept the gospel, but those who have thus procrastinated their acceptance of the saving truths will not gain salvation in the celestial kingdom of God. Salvation for the dead is limited expressly to those who do not have opportunity in this life to accept the gospel but who would have taken the opportunity had it come to them. There is no promise in any revelation that those who have a fair and just opportunity in this life to accept the gospel, and who do not do it, will have another chance in the spirit world to gain celestial salvation.
In other words, entrance into the Celestial salvation is available only to those in spirit-prison who have never had an opportunity during their mortal lives to hear and understand the LDS restored gospel, and based on the foreknowledge of God would have become Mormons if they had had the chance. Dr. Stephen Robinson clarifies:
Persons who did not have the opportunity of baptism presented to them during their lives may still inherit the celestial kingdom if in the infinite foreknowledge of God they would have received it given the opportunity. In the LDS view it is only those who have heard the gospel fairly and correctly presented, who understand it correctly, who feel a witness of the Spirit and who yet refuse to accept it who will bring their spiritual progress to a halt.
Thus, everyone, even family members of worthy Mormons, who understood, rejected, or were unfaithful to the LDS restored gospel during their earthly lives will have the opportunity to enter only the Terrestrial or Telestial kingdom following the final judgment of God. This means that, in the end, they will be eternally separated from their family members who go to the Celestial kingdom, whether temple family sealings were performed for them or not. Personal worthiness is the Mormon assurance or guarantee concerning whether family units will dwell together for eternity, and not temple family sealings.