Question: "Why are Mormons/LDS so interested in genealogies?"
Answer: Many do not know that one of the biggest influences in the recent genealogy craze is the Church of Jesus Christ of Latter Day Saints (LDS), also known as the Mormons. The LDS interest in genealogies is connected to their belief in and practice of “baptism for the dead.”
The LDS church believes that several ordinances, including baptism, must be fulfilled for a person to be saved (Doctrine and Covenants 84:19-21). The LDS church also teaches that members in good standing can fulfill these ordinances in the place of ancestors who have passed on without the opportunity to do so (Doctrine & Covenants 124:93). The church says that, once the ordinances are fulfilled and the person accepts the gospel of Jesus Christ (even if heard and accepted after death), he or she can move on to a higher kingdom (Doctrine & Covenants 76). LDS members use genealogy to discover who their ancestors are and fulfill the covenants in their stead.
These beliefs are faulty in several ways. First, there is only one way to salvation, and that is through faith in the Lord Jesus Christ. Ordinances and sacraments are works, and therefore, not required (Ephesians 2:8–9). Second, no person can earn the salvation of another. “So faith comes from hearing, and hearing by the word of Christ” (Romans 10:17). It does not come by someone else being baptized or completing ordinances in your name.
There is nothing wrong with studying genealogies. Jesus’ ancestry is given in Matthew 1 and Luke 3. But once a person has passed on, his chance to come to a saving relationship with Christ is over.
(Editor’s note: many of the references in our articles on Mormonism are Mormon publications, such as Mormon Doctrine, Articles of Faith, Doctrines of Salvation, History of the Church, Doctrine and Covenants, and so forth. Others are from the Book of Mormon itself, e.g., books such as 1 Nephi, 2 Nephi, and Alma.)