James T. Duke, “Eternal Marriage,” in Latter-day Saint Essentials: Readings from the Encyclopedia of Mormonism,ed. John W. Welch and Devan Jensen (Provo, UT: BYU Studies and the Religious Studies Center, Brigham Young University, 2002), 105–8.
The principle of eternal marriage and the ordinances implementing it constitute a very distinctive and valuable part of the Church. It involves a ceremony performed in a holy temple by an officiator endowed with the priesthood authority to invoke covenants intended to be efficacious for time and eternity. This is a sacred and simple ceremony to unite husband and wife in the bonds of everlasting love and in the hopes of eternity. President Joseph Fielding Smith taught that such a marriage involves “an eternal principle ordained before the foundation of the world and instituted on this earth before death came into it,"  for Adam and Eve were given in marriage to each other by God in the Garden of Eden before the Fall (Gen. 2:22–25; Moses 3:22–25). This sacred act of marriage was the crowning act of all creation: “In the day that God created man, in the likeness of God made he him: male and female created he them; and blessed them” (Gen. 5:1–2). With his blessing they truly could set the pattern for their descendants thereafter who two by two, a man and a woman, could leave father and mother, cleave to each other, and “be one flesh” (Gen. 2:24). Thus began the great plan of God for the happiness of all his children.
Latter-day Saints believe that life is more secure and more joyous when it is experienced in the sacred relationships of the eternal family. Those who maintain such worthy relationships on earth will live as families in the celestial kingdom following the resurrection. Thus, a person who lives a righteous life in mortality and who has entered into an eternal marriage may look forward to an association in the postmortal world with a worthy spouse, and with those who were earthly children, fathers, mothers, brothers, and sisters. Bruce R. McConkie, an apostle, explained that an eternal family starts with “a husband and a wife, united in a family unit. It then goes out to our children—the spirits that God gives us to be members of our family—to our grandchildren and so on, to the latest generation. It also reaches back to our parents and our grandparents to the earliest generation.”  President Brigham Young said that eternal marriage “is the thread which runs from the beginning to the end of the holy Gospel of Salvation—of the Gospel of the Son of God; it is from eternity to eternity."
Even as marriage marks an apex in God’s creative processes, so, too, it is for each person the sacred culmination of the covenants and ordinances of the priesthood of God and, indeed, is truly a new and everlasting covenant (D&C 131:2). Eternal marriage is a covenant, a sacred promise that a wife and a husband make with each other and with God, attested to by both mortal witnesses and heavenly angels. Under proper conditions such marriages are sealed by the Holy Spirit of Promise, and the couple, through their faithfulness, can eventually inherit exaltation and glory in the celestial kingdom of God (D&C 132:19). The scriptures confirm that eternal marriage, performed by the authority of the priesthood, sealed or affirmed by the Holy Ghost, and sustained by a righteous life, “shall be of full force” after death (D&C 132:19; cf. 1 Cor. 11:11). The phrase “until death do you part” is regarded as a tragic one that predicts the ultimate dissolution of the marriage, and this phase is not stated in the temple marriage ceremony.
The sacred ceremony of temple marriage is conducted in reverence and simplicity, and the occasion is a beautiful and joyous one for Latter-day Saints. The bride and the groom meet with family and friends in a designated sealing room of the temple. The officiator typically greets the couple with a few words of welcome, counsel, and fatherly commendations. He may admonish the couple to treat each other throughout life with the same love and kindness that they feel at this moment, and may add other words of encouragement, with his blessing upon their righteous undertaking. The couple is invited to come forward and kneel facing each other across an altar in the middle of the room. The sealer sometimes directs the attention of all present to the mirrors on opposite walls, reflecting endlessly the images of the couple at the altar, and he may comment on the symbolism. Then the sealer pronounces the simple words of the ceremony, which promise, on condition of obedience, lasting bonds with the potential for eternal joy between these two sealed for eternity. President Ezra Taft Benson said, “Faithfulness to the marriage covenant brings the fullest joy here and glorious rewards hereafter."  At the conclusion of the ceremony, the couple kiss over the altar and may then arise and leave the altar to exchange rings.
Through this ordinance of eternal marriage, men and women commit themselves in pure love to remain true to each other and to God through all eternity. Divorce is discouraged, and couples are taught to confine their intimate affections and sexuality solely to each other. To undertake and honor the covenants of temple marriage require living in ways that contribute to happy and successful family life. A couple’s future may include conflicts and even divorce, which when it occurs is often a result of violating temple covenants; but the divorce rate among couples who have been sealed in a temple is very low.
Eternal marriage is, of course, not just for the blessing, happiness, or benefit of the spouses. It is an act of service, commitment, and love that blesses the next generation. God commanded Adam and Eve to “be fruitful, and multiply, and replenish the earth” (Gen. 1:28). A primary purpose of temple marriage in this life is to grow and mature in sharing God’s creative work in raising a family in righteousness. Parents enter into a partnership with God by participating in the procreation of mortal bodies, which house the spirit children of God. At some future time all the worthy sons and daughters of God will be reunited with their heavenly parents as one eternal extended family in a state of resurrected glory.
People who live a worthy life but do not marry in the temples, for various reasons beyond their control, which might include not marrying, not having heard the gospel, or not having a temple available so that the marriage could be sealed for eternity, will at some time be given this opportunity. Latter-day Saints believe it is their privilege and duty to perform these sacred ordinances vicariously for deceased progenitors, and for others insofar as possible. Most of the sealing ordinances (temple marriage ceremonies) performed for the deceased are for couples who were married by civil authority in mortality but died without hearing the fulness of the gospel. In this program of vicarious service, men and women meet by appointment in the temple where they stand as proxies for parents, grandparents, or others who have passed into the next world and make the solemn covenants that will reach fruition for all who accept them in the spirit world, to culminate in the day of resurrection.
All leaders of the Church encourage couples to initiate their marriage vows in a holy temple. For those who do not, whether converts to the Church, LDS couples coming to devotion to the Church in later life, or young LDS couples who have married outside the temple and then felt the desire for eternal covenants, temple marriage is a renewal of vows first spoken in a civil marriage ceremony. For those commitments to be honored through eternity, couples must be married by an officiator having the power to bind on earth and in heaven (Matt. 16:19; D&C 124:93). Thus, they must go to a temple, where there are those ordained and appointed to the power to seal covenants for time and eternity.
For Latter-day Saints, eternal marriage is an avenue to everlasting joy. Matthew Cowley, an apostle, expressed his conviction that it is “a wonderful thing . . . to kneel at an altar in the temple of God, clasping the hand of one who is to be your companion not only for time, but also for all eternity, and then to have born into that sacred and eternal covenant children for eternity. God is love. Love is eternal. Marriage is the sweetest and most sacred expression of love, therefore, marriage is eternal."
 Smith, Joseph Fielding. The Way to Perfection. Salt Lake City, 1931.
 McConkie, Bruce R. “The Eternal Family Concept.” In Genealogical Devotional Addresses, pp. 81–93. Second Annual Priesthood Genealogical Research Seminar, Brigham Young University. Provo, Utah, 1967.
 Young, Brigham. Discourses of Brigham Young, ed. John A. Widtsoe, Salt Lake City, 1971.
 Benson, Ezra Taft. The Teachings of Ezra Taft Benson. Salt Lake City, 1988.
 Cowley, Matthew. Matthew Cowley Speaks. Salt Lake City, 1954.
For Further Reading, also see:
Brown, Hugh B. You and Your Marriage. Salt Lake City, 1960.
Burton, Theodore M. God’s Greatest Gift. Salt Lake City, 1976.