23 For all have sinned, and come short of the glory of God;
24 Being justified freely by his grace through the redemption that is in Christ Jesus:
25 Whom God hath set forth to be a propitiation through faith in his blood, to declare his righteousness for the remission of sins that are past, through the forbearance of God;
26 To declare, I say, at this time his righteousness: that he might be just, and the justifier of him which believeth in Jesus.
27 Where is boasting then? It is excluded. By what law? of works? Nay: but by the law of faith.
28 Therefore we conclude that a man is justified by faith without the deeds of the law.
Note that when Paul speaks of the law in verse 28, he is referring to the Law of Moses and the term, “without” in the original Greek is “apart from” or “without intervention of”.
Although the word “justify” has several meanings, its main meaning in the latter-day scriptures is inseparably intertwined with the concepts of grace (Rom. 3:28; Gal. 2:16; 2 Ne. 2:5; Mosiah 14:11; D&C 20:30; Moses 6:60), faith, repentance, righteousness, and sanctification.
Justification is a scriptural metaphor drawn from the courts of law: a judge justifies an accused person by declaring or pronouncing that person innocent. Likewise, God may treat a person as being “not guilty” of sin. All mortals individually need to be justified because they fall short of perfect obedience to God, becoming “carnal, sensual, and devilish” through transgression (Moses 5:13; Mosiah 16:3), are “cut off” from God, and are in jeopardy of becoming “miserable forever” (2 Ne. 2:5). In this plight, they of themselves cannot be justified through subsequent obedience to the law and cannot change their own nature to become obedient. Furthermore, they are severed from the source of the divine power that can change, or sanctify, them (2 Ne. 9:5-9).
However, through the Atonement of Jesus Christ, when men, women, or children have faith in Jesus, are truly penitent, call upon his name, and are baptized, they become eligible for the redeeming grace extended through Jesus Christ. In this sense they become justified. This is given as a gift by grace, since fallen man must rely “alone upon the merits of Christ” (1 Ne. 10:6; Moro. 6:4). The faith by which one receives this grace manifests itself in an active determination to follow Christ in all things. It is demonstrated by obedience to the commandments to repent and be baptized, followed by a life of submission, obedience, and service to God and others (2 Ne. 31:16-20; Moro. 8:25-26; see Gospel of Jesus Christ).
Justification directly opens the way to sanctification by establishing a “right” relationship of mortals with God. Thus, God, without denying justice, can bless them with the sanctifying power of the Holy Ghost (Mosiah 5:1-2; 3 Ne. 27:20). Justification starts the believer on the path toward righteousness.
Author: Colin B. Douglas, The Encyclopedia of Mormonism
To be sanctified through the blood of Christ is to become clean, pure, and holy. If justification removes the punishment for past sin, then sanctification removes the stain or effects of sin.
Elder D. Todd Christofferson
“Justification and Sanctification,” Ensign, Jun 2001, 18
For by the water ye keep the commandment; by the Spirit ye are justified, and by the blood ye are sanctified.