On Mount Sinai, the Lord commanded, “Thou shalt not commit adultery” (Exodus 20:14). The prophet Abinadi reiterated this commandment as he spoke to the priests of King Noah. (See Mosiah 13:22.) A number of years later, priests led by Alma denounced “adultery, and all manner of lasciviousness, crying that these things ought not so to be” (Alma 16:18).
The Savior took this injunction even further. During His mortal ministry, He declared, “whosoever looketh on a woman to lust after her hath committed adultery with her already in his heart” (Matthew 5:27-28, 3 Nephi 12:27-28). And in 1831, He expanded on this principle:
Thou shalt love thy wife with all thy heart, and shalt cleave unto her and none else.
And he that looketh upon a woman to lust after her shall deny the faith, and shall not have the Spirit; and if he repents not he shall be cast out.
Doctrine and Covenants 42:22-23 (See also Doctrine and Covenants 63:16.)
Why is adultery and even lust—the desire to commit adultery—so serious? Elder Jeffrey R. Holland gave the following explanation:
Why is lust such a deadly sin? Well, in addition to the completely Spirit-destroying impact it has upon our souls, I think it is a sin because it defiles the highest and holiest relationship God gives us in mortality—the love that a man and a woman have for each other and the desire that couple has to bring children into a family intended to be forever. Someone said once that true love must include the idea of permanence. True love endures. But lust changes as quickly as it can turn a pornographic page or glance at yet another potential object for gratification walking by, male or female….
Prostituting the true meaning of love—either with imagination or another person…destroys that which is second only to our faith in God—namely, faith in those we love. It shakes the pillars of trust upon which present—or future—love is built, and it takes a long time to rebuild that trust when it is lost.
“Place No More for the Enemy of My Soul,” General Conference, April 2010
That explanation rings true to me. Adultery and lust are inherently impermanent. If you want to build eternal relationships, you have to be capable of making permanent commitments. Relationships don’t just happen; they are built. We build them by acting in a way that fosters trust and then maintaining that trust over time.
Today, I will be grateful for the most important relationships in my life, particularly my relationship with my wife. I will remember that the permanence of a relationship is dependent on the permanence of my trustworthiness. I will strive to act, talk and think in a way that builds trust and strengthens my most important relationships.
Book of Mormon Study Notes 