Mormons are well-known for their interest in genealogy because they believe it is their responsibility to be baptized on behalf of the dead. They believe those who have died without accepting Mormonism can still make it to heaven if their names are taken to the Temple and someone is baptized on their behalf. Because they don’t have a body, the ordinance is done for them by proxy, giving the dead the opportunity to accept Mormonism in the spirit world. Mormons base this practice on 1 Cor. 15:29, but Paul disassociates himself from the pagan practice by using the word “they,” not “we.”
Some Mormons are even married on behalf of the dead, by going through the marriage ceremony in their place. This supposedly enables a dead person to make it out of “Spirit Prison” and into a higher level of heaven.
1 Corinthians 15:29 Otherwise, what will they do who are baptized for the dead, if the dead do not rise at all? Why then are they baptized for the dead?