Sexual sin is particularly abominable to the Lord because it abuses the procreative privilege. That procreative ability is sacred, and in fact, is a characteristic of divinity. Boyd K. Packer has stated, “the power of procreation is not an incidental part of the plan of happiness, it is the key—the very key.” (Latter-day Commentary on the Book of Mormon compiled by K. Douglas Bassett, p. 331)
David O. McKay
“A dominant evil of the world today is unchastity. I repeat what appeared over the signature of President Joseph F. Smith while he was living: ’No more loathsome cancer disfigures the body and soul of society today than the frightful affliction of sexual sin. It vitiates the very fountains of life, and bequeaths its foul effects to the yet unborn as a legacy of death.’ (The Improvement Era, Vol. 20, p. 739.) He who is unchaste in young manhood is untrue to a trust given him by the parents of the girl; and she who is unchaste in maidenhood is untrue to her future husband and lays the foundation of unhappiness, suspicion, and discord in the home.” (Conference Report, Apr. 1969, p. 6)
First Presidency Message
"The doctrine of this Church is that sexual sin--the illicit sexual relations of men and women--stands, in its enormity, next to murder.
"The Lord has drawn no essential distinctions between fornication, adultery, and harlotry or prostitution. Each has fallen under His solemn and awful condemnation.
"You youths of Zion, you cannot associate in non-marital, illicit sex relationships, which is fornication, and escape the punishments and the judgments which the Lord has declared against this sin. The day of reckoning will come just as certainly as night follows day. They who would palliate this crime and say that such indulgence is but a sinless gratification of a normal desire, like appeasing hunger and thirst, speak filthiness with their lips. Their counsel leads to destruction; their wisdom comes from the Father of Lies.
"You husbands and wives who have taken on solemn obligations of chastity in the holy temples of the Lord and who violate those sacred vows by illicit sexual relations with others, you not only commit the vile and loathsome sin of adultery, but you break the oath you yourselves made with the Lord Himself before you went to the altar for your sealing. You become subject to the penalties which the Lord has prescribed for those who breach their covenants with Him.
“…By virtue of the authority in us vested as the First Presidency of the Church, we warn our people who are offending, of the degradation, the wickedness, the punishment that attend upon unchastity; we urge you to remember the blessings which flow from the living of the clean life.” (Heber J. Grant, J. Reuben Clark, Jr., and David O. McKay, Conference Report, Oct. 1942, pp. 11-12)
Spencer W. Kimball
“It is not the soil of earth or the grease on a person’s hands that defile him; nor is it the fingernails ’edged in black,’ the accumulated perspiration from honest toil, or the body odor resulting from heavy work. One may bathe hourly, perfume oneself often, have hair shampooed frequently, have fingernails manicured daily, and be a master at soft-spoken utterances, and still be as filthy as hell’s cesspools. What defiles is sin, and especially sexual sin.” (The Miracle of Forgiveness, p. 62)