See also: D&C 133
Elder Bruce R. McConkie explained: “To be sanctified is to become clean, pure, and spotless; to be free from the blood and sins of the world; to become a new creature of the Holy Ghost, one whose body has been renewed by the rebirth of the Spirit. Sanctification is a state of saintliness, a state attained only by conformity to the laws and ordinances of the gospel. The plan of salvation is the system and means provided whereby men may sanctify their souls and thereby become worthy of a celestial inheritance.
“Sanctification is a basic doctrine of the gospel (D. & C. 20:31–34); indeed, the very reason men are commanded to believe, repent, and be baptized is so they ‘may be sanctified by the reception of the Holy Ghost,’ and thereby be enabled to stand spotless before the judgment bar of Christ. (2 Ne. 27:19–21)” (Mormon Doctrine, p. 675)
Since the scriptures teach that no unclean thing can dwell in His presence (see Moses 6:57), it is clear that the Saints who are caught up to meet Him must be sanctified. — Doctrine and Covenants Student Manual, p 336
An angry mob approached Edward Partridge, the Bishop of the Church, and he related this story in his autobiography:
“I was taken . . . to the court house on the public square in Independence; . . surrounded by hundreds of the mob. I was stripped of my hat, coat and vest and daubed with tar from head to foot, and then had a quantity of feathers put upon me. . . .
“I told them that the Saints had suffered persecution in all ages of the world; . . that I was willing to suffer for the sake of Christ. . . .
“I bore my abuse with so much resignation and meekness, that it appeared to astound the multitude, who permitted me to retire in silence, many looking very solemn, their sympathies having been touched as I thought; and as to myself, I was so filled with the Spirit and love of God, that I had no hatred towards my persecutors or anyone else.” — History of the Church 1:390
Joseph Smith taught, “The nearer we get to our heavenly Father, the more we are disposed to look with compassion on perishing souls; we feel that we want to take them upon our shoulders, and cast their sins behind our backs….If you would have God have mercy on you, have mercy on one another.” (Teachings of the Prophet Joseph Smith, p. 241) — Glenn L. Pace, Spiritual Plateaus, p. 89
I will put my own definition to the term sanctification, and say it consists in overcoming every sin and bringing all into subjection to the law of Christ. God has placed in us a pure spirit; when this reigns predominant, without let or hindrance, and triumphs over the flesh and rules and governs and controls as the Lord controls the heavens and the earth, this I call the blessing of sanctification. . . . (Brigham Young, Journal of Discourses, 10:173) — Doctrine and Covenants Student Manual, p. 41