This is a poster that I found in the gift shop of the Church History Museum in Salt Lake city, Utah. Baptism for the dead is an important belief in the LDS faith. Latter day saints believe that baptism is necessary for salvation.
"Jesus Christ taught that baptism is essential to the salvation of all who have lived on earth (see John 3:5). Many people, however, have died without being baptized. Others were baptized without proper authority. Because God is merciful, He has prepared a way for all people to receive the blessings of baptism. By performing proxy baptisms in behalf of those who have died, Church members offer these blessings to deceased ancestors. Individuals can then choose to accept or reject what has been done in their behalf." - Baptism for the dead explained on www.lds.org
A verse they mention to back up their understanding is John 3:5. "Jesus answered, Verily, verily, I say unto thee, Except a man be born of water and of the Spirit, he cannot enter into the kingdom of God." But they fail to read the very next verse, (v6) "That which is born of the flesh is flesh; and that which is born of the Spirit is spirit." The "water' in verse 5 is referring to the womb. For Example when a women's water breaks.
Eternal life is only found in Jesus Christ, not by the works we do here on earth or the works someone does for us.
