The Salt Lake Temple Baptismal Font
The baptismal font is located in the baptistry on the basement floor of the Salt Lake Temple. The LDS Church teaches that baptism by immersion is a priesthood ordinance that is required for a person's eternal salvation (Mark 16:15-16). When someone is baptized into the LDS Church that baptism is usually performed in a font located in a local church building. The baptismal font in the Salt Lake Temple, and in other LDS temples, is set apart specifically to perform proxy baptisms on behalf of deceased persons. We believe that those who died without having the opportunity to learn about the gospel of Jesus Christ, and either accept it or reject it, will have the chance to be taught in the next life prior to final judgment. Learn more about the bible foundation for our belief in salvation for the dead.
To complete the baptism, the priesthood holder who is performing the baptism, and the person acting as proxy for the deceased individual, stand together in the baptismal font. The priesthood holder states the name of the deceased and that the person is being baptized in the name of The Father, of The Son and of The Holy Ghost. The proxy is then baptized by complete immersion. Two witnesses sitting next to the font observe to make sure the baptism is performed correctly. If not, the ceremony is repeated.
Everything about the temple is designed to teach gospel principles through symbolism; including the baptistry and font. For example, the baptistry is always located on the bottom floor of the temple, symbolizing the beginning of the person's path along God's Plan of Salvation. Proxies are baptized by complete immersion to symbolize being buried with and rising again with Jesus Christ. The font itself sits on the back of twelve oxen which represent the twelve tribes of Israel, and is a replica of the brazen sea that sat upon twelve oxen in the Temple of Solomon, as described in the Old Testament Book of Jeremiah.
Names of deceased persons vicariously baptized are not added to LDS Church membership rolls and are not counted in LDS Church membership numbers. Deceased persons are not considered de facto Mormons. They are still free to choose to accept or reject the baptism that was performed on their behalf. The practice is a demonstration of God's mercy and justice because it shows we're all judged the same, instead of God judging people on different standards based on where and when they were born.
Learn more at the official LDS Church website.