From The Encyclopedia of Mormonism
Author: Garrett, H. Dean
Once a person joins The Church of Jesus Christ of Latter-day Saints, circumstances requiring rebaptism are unusual. In current policy and practice, a person would be rebaptized only in two cases: (1) if membership records were irretrievably lost and no other proof of membership could be established; or (2) if an excommunicated person qualified for reentry into the Church. As members partake of the Sacrament weekly, repenting of sin, their baptismal covenants are renewed and rebaptism is unnecessary.
One enters into membership in the Church only through baptism by immersion for the remission of sins by one holding the appropriate priesthood, regardless of any prior baptism or initiation ordinance. Latter-day scriptures refer to baptism as a new and everlasting covenant. It is the ordinance received by one who accepts the gospel of Jesus Christ, with the promise that proper baptism opens onto the path that leads to eternal life. But baptisms performed outside the framework of the restored priesthood are of no avail for one who wishes to enter in at the strait gate and onto that path (D&C 22:1-2).
Rebaptism is rare among Latter-day Saints in modern times. Historically, however, many members were rebaptized as an act of rededication. This was first practiced in Nauvoo and was continued in the Utah Territory. Rebaptism served as a ritual of recommitment but was not viewed as essential to salvation. Members often sought rebaptism when called to assist in colonization or to participate in one of the united orders. On some occasions, the Saints were rebaptized as they prepared for marriage or entrance into the temple. Early members also rebaptized some of the sick among them as an act of healing. Because of misuse by some Church members, all such practices of rebaptism were discontinued in 1897. H. DEAN GARRETT