Thy righteousness is an everlasting righteousness, and thy law is the truth. Psalm 119:142. RC 48.1
Erroneous theories of sanctification ... have a prominent place in the religious movements of the day. These theories are both false in doctrine and dangerous in practical results; and the fact that they are so generally finding favor renders it doubly essential that all have a clear understanding of what the Scriptures teach upon this point. RC 48.2
True sanctification is a Bible doctrine. The apostle Paul, in his letter to the Thessalonian church, declares: “This is the will of God, even your sanctification.” And he prays: “The very God of peace sanctify you wholly” (1 Thessalonians 4:3; 5:23). The Bible clearly teaches what sanctification is and how it is to be attained. The Saviour prayed for His disciples: “Sanctify them through thy truth: thy word is truth” (John 17:17). And Paul teaches that believers are to be “sanctified by the Holy Ghost” (Romans 15:16). RC 48.3
What is the work of the Holy Spirit? Jesus told His disciples: “When he, the Spirit of truth, is come, he will guide you into all truth” (John 16:13). And the psalmist says: “Thy law is the truth.” ... And since the law of God is “holy, and just, and good,” a transcript of the divine perfection, it follows that a character formed by obedience to that law will be holy. RC 48.4
Christ is a perfect example of such a character. He says: “I have kept my Father's commandments.” “I do always those things that please him” (John 15:10; 8:29). The followers of Christ are to become like Him—by the grace of God to form characters in harmony with the principles of His holy law. This is Bible sanctification. RC 48.5
This work can be accomplished only through faith in Christ, by the power of the indwelling Spirit of God. Paul admonishes believers: “Work out your own salvation with fear and trembling. For it is God which worketh in you both to will and to do of his good pleasure” (Philippians 2:12, 13). The Christian will feel the promptings of sin, but he will maintain a constant warfare against it. Here is where Christ's help is needed. Human weakness becomes united to divine strength, and faith exclaims: “Thanks be to God, which giveth us the victory through our Lord Jesus Christ” (1 Corinthians 15:57). RC 48.6
The Scriptures plainly show that the work of sanctification is progressive. When in conversion the sinner finds peace with God through the blood of the atonement, the Christian life has but just begun. Now he is to “go on unto perfection”; to grow up “unto the measure of the stature of the fulness of Christ.”—The Great Controversy, 469, 470. RC 48.7