Bruce R. McConkie
"We clean our garments by washing them in water. Filth, dirt, germs, odors, and whatever is unclean and offensive is thus removed; our wearing apparel becomes clean and spotless. A saved person is one whose soul is clean and spotless, one who is free from the filth and corruption of sin; and the prophetic way of describing such a person is to say that his garments are clean. Since the only way a human soul can be cleansed and perfected is through the atonement of Christ, it follows that the symbolic way of describing this process is to say that such a one has washed his garments in the blood of the Lamb, as we have here learned Nephi and Alma did." (The Promised Messiah, p. 251)
The stain of blood is not easy to clean. Yet, the Savior's blood is able to cleanse that which we have spilt through sin, though your sins be as scarlet, they shall be as white as snow; though they be red like crimson, they shall be as wool (Isa 1:18). Without the power of his redemption, all of us would stand before the bar of God, having our garments stained with blood; yet the Savior would still wear a glorious, white robe. Through the power of his redemption, this pattern is reversed. On Judgment Day, the righteous are arrayed in white robes (Rev 7:13), while the Lord shall be red in his apparel, and his garments like him that treadeth in the wine-vat (DC 133:48). Why are his garments red? They will be red to represent the day of vengeance when the wicked are justly destroyed because they would not have their garments washed white through the blood of his atoning sacrifice, their blood have I sprinkled upon my garments, and stained all my raiment; for this was the day of vengeance which was in mine heart (DC 133:51).
Joseph Fielding McConkie comments on how the endowment symbolizes the same process:
"This endowment and its blessings of power, authority, and protection were, we are told, also enjoyed by 'Seth, Noah, Melchizedek, Abraham [they being representatives of the principle], and all to whom the Priesthood was [has been] revealed' (Abraham, Facsimile 2, figure 3). As the gospel is everlasting, so are its ordinances, and as we have previously seen, those who stand in the presence of the Lord (symbolically the temple) must be properly clothed, and hence have put upon them the garment of the priesthood and the robes of righteousness. This is as much a part of the endowment and temple ritual today as it ever was in ages past. Alma testified that none could enter the kingdom of heaven except they be so clothed and their garments be washed white through the blood of Christ. Of the wicked whose garments would be stained with sin he asked, 'Do ye suppose that such an one can have a place to sit down in the kingdom of God, with Abraham, with Isaac, and with Jacob, and also all the holy prophets, whose garments are cleansed and are spotless, pure and white?' (Alma 5:21-24.)" (Joseph Fielding McConkie, Gospel Symbolism, pp. 202-3)