I’ve been asked this question more than a few times. It is usually followed by something like, “Do they worship their dead ancestors?”
The truth is, we believe in a God who loves His children so much, that He gives each person every chance possible to accept His Gospel and follow Him in the gospel path.
Think about it, how many people in the world have died without ever even hearing the name of Jesus Christ, and yet no man can come to the Father, but by Him. How many others have heard, but their life circumstances didn’t enable them to receive His word? Would a loving God condemn all these, who never received the gospel at no fault of their own? Absolutely Not!
We believe in a God who gives each person every possible chance to enable them to receive His Gospel. And if that chance doesn’t come in his life, then it will come in the Spirit World, before the resurrection.
The New Testament preaches of this doctrine as well. “For Christ also hath once suffered for sins, the just for the unjust, that he might bring us to God, being put to death in the flesh, but quickened by the Spirit: By which also he went and preached unto the spirits in prison; Which sometime were disobedient, when once the longsuffering of God waited in the days of Noah, while the ark was a preparing, wherein few, that is, eight souls were saved by water.” (1 Peter 3:18-20)
“For for this cause was the gospel preached also to them that are dead, that they might be judged according to men in the flesh, but live according to God in the spirit.” (1 Peter 4:6)
“Else what shall they do which are baptized for the dead, if the dead rise not at all? why are they then baptized for the dead?” (1 Corinthians 15:29)
You see, after Jesus Christ’s death, but before His resurrection, he visited the Spirit World, and there he organized groups of men and women to go into the Spirit Prison, unto those who never received the gospel. Since that time, spirit missionaries have preached the gospel to our deceased ancestors, and many have accepted the gospel, and are ready for the next step of their spiritual progression.
Their next step is Baptism. These ordinances, however, cannot be done as spirits, for a body is required for a person to be baptized in water. So Mormons do baptisms and other work in behalf of their deceased ancestors.
Ordinances for the dead are only done inside one of our Temples, and each ordinance is done one-by-one, which, when you consider how many people have died, will take us a long time to complete. It is an act of love by our loving Heavenly Father, and by the faithful LDS members who use geneology to seek out their ancestors and do the ordinances for them.
The final ordinance done for them is called Sealing, wherein a person is sealed to their spouse, children and parents. This act creates a binding link between generations, and links those living with those deceased.
Mormons believe that the eternal goal God has for His children is to live with him and with our families. Therefore, inside a holy temple a couple can be married for this life and for all eternity, not just till death do us part. This doctrine brings much peace to those who have lost young loved ones to death.