Why do Mormons perform baptisms for the dead?
Jesus Himself, though without sin, was baptized to fulfill all righteousness and to show the way for all mankind (see Matthew 3:13-17; 2 Nephi 31:5-12). Thus, baptism is essential for salvation in the kingdom of God. We learn in the New Testament that baptisms for the dead were done during the Apostle Paul’s time (see 1 Corinthians 15:29). This practice has been restored with the establishment of The Church of Jesus Christ of Latter-day Saints. The Prophet Joseph Smith first taught about the ordinance of baptism for the dead during a funeral sermon in August 1840. He read much of 1 Corinthians 15, including verse 29, and announced that the Lord would permit Church members to be baptized in behalf of their friends and relatives who had departed this life. He told them “the plan of salvation was calculated to save all who were willing to obey the requirements of the law of God” (Journal History of the Church, 15 Aug. 1840).
Because all who have lived on the earth have not had the opportunity to be baptized by proper authority during life on earth, baptisms may be performed by proxy, meaning a living person may be baptized in behalf of a deceased person. Baptisms for the dead are performed by Church members in temples throughout the world. People have occasionally wondered if the mortal remains of the deceased are somehow disturbed in this process; they are not. The person acting as a proxy uses only the name of the deceased. To prevent duplication the Church keeps a record of the deceased persons who have been baptized. Some have misunderstood that when baptisms for the dead are performed the names of deceased persons are being added to the membership records of the Church. This is not the case.