One of Joseph Smith’s most radical teachings is the principle that Godhood is couplehood: angels abide singly, Gods live in families (D&C 132). For Latter-day Saints, therefore, marriage is not merely an “honorable state,” but the means by which human beings open themselves up to the full measure of God’s blessings, including a fullness of joy. The marriages solemnized in temples are “sealed” both on earth and in heaven (a concept derived from Matthew 16:19). Sealed marriages are understood to endure for eternity as well as for time, which means, among other things, that the couple can have eternal progeny–“a continuation of the seeds forever and ever” (D&C 132:19). That last concept scandalizes orthodox Christians but opens the door to an extraordinarily positive understanding of human sexuality.
The sealing rite functions as a marriage ceremony, but the rite can also be used to seal couples who have been married outside the temple. The sealing of spouses extends to their children: that is, children born to a sealed couple are said to be born “under the covenant” and will be united with their parents in eternity. When a couple who were wed outside the temple have their marriage sealed, a brief, separate rite seals to the couple any children born outside the covenant. Both rites–the sealing of spouses and the sealing of children to parents–can also be performed vicariously for the dead.