The priesthood power to bind families eternally is one of the greatest gifts of God. Every person who understands the plan of salvation longs for that lasting blessing. Only in sealing ceremonies performed in dedicated temples of The Church of Jesus Christ of Latter-day Saints does God offer the promise that families can be bound together forever.
The priesthood keys that make this possible were restored to the earth by the prophet Elijah to Joseph Smith in the Kirtland Temple. Those priesthood keys have been passed in an unbroken line through living prophets in The Church of Jesus Christ of Latter-day Saints to the present day.
Supplement: Read Robert D. Hales' April 1999 Conference address "Strengthening Famliies: Our Sacred Duty"
The words of living prophets are clear regarding our sacred duty to strengthen our families spiritually. In 1995 the First Presidency and the Council of the Twelve Apostles issued a proclamation to the world, declaring that “the family is central to the Creator’s plan for the eternal destiny of His children. … Husband and wife have a solemn responsibility to love and care for each other and for their children. … Parents have a sacred duty to rear their children in love and righteousness, to provide for their physical and spiritual needs, to teach them to love and serve one another, [and] to observe the commandments of God” (“The Family: A Proclamation to the World,” Ensign, Nov. 1995, 102; Liahona, June 1996, 10–11).