The New Testament indicates that baptisms for the dead were done during the time of the Apostle Paul (see 1 Corinthians 15:29). This ordinance was restored with the establishment of The Church of Jesus Christ of Latter-day Saints.

Detta är ett tal av D. Todd Christofferson som också förklarar det bra.

Christian theologians have long wrestled with the question, What is the destiny of the countless billions who have lived and died with no knowledge of Jesus?

¹ With the Restoration of the gospel of Jesus Christ has come the understanding of how the unbaptized dead are redeemed and how God can be “a perfect, just God, and a merciful God also.”

²While yet in life, Jesus prophesied that He would also preach to the dead.

³ Peter tells us this happened in the interval between the Savior’s Crucifixion and Resurrection.

⁴ President Joseph F. Smith witnessed in vision that the Savior visited the spirit world and “from among the righteous [spirits] … organized his 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. …

“These were taught faith in God, repentance from sin, vicarious baptism for the remission of sins, [and] the gift of the Holy Ghost by the laying on of hands.”

⁵The doctrine that the living can provide baptism and other essential ordinances to the dead, vicariously, was revealed anew to the Prophet Joseph Smith.

⁶ He learned that the spirits awaiting resurrection are not only offered individual salvation but that they can be bound in heaven as husband and wife and be sealed to their fathers and mothers of all generations past and have sealed to them their children of all generations future. The Lord instructed the Prophet that these sacred rites are appropriately performed only in a house built to His name, a temple.

⁷The principle of vicarious service should not seem strange to any Christian. In the baptism of a living person, the officiator acts, by proxy, in place of the Savior. And is it not the central tenet of our faith that Christ’s sacrifice atones for our sins by vicariously satisfying the demands of justice for us? As President Gordon B. Hinckley has expressed: “I think that vicarious work for the dead more nearly approaches the vicarious sacrifice of the Savior Himself than any other work of which I know. It is given with love, without hope of compensation, or repayment or anything of the kind. What a glorious principle.”

⁸Some have misunderstood and suppose that deceased souls “are being baptised into the Mormon faith without their knowledge”

⁹ or that “people who once belonged to other faiths can have the Mormon faith retroactively imposed on them.”

¹⁰ They assume that we somehow have power to force a soul in matters of faith. Of course, we do not. God gave man his agency from the beginning.

¹¹ “The dead who repent will be redeemed, through obedience to the ordinances of the house of God,”

¹² but only if they accept those ordinances. The Church does not list them on its rolls or count them in its membership.

Our anxiety to redeem the dead, and the time and resources we put behind that commitment, are, above all, an expression of our witness concerning Jesus Christ. It constitutes as powerful a statement as we can make concerning His divine character and mission. It testifies, first, of Christ’s Resurrection; second, of the infinite reach of His Atonement; third, that He is the sole source of salvation; fourth, that He has established the conditions for salvation; and, fifth, that He will come again.