Sanctification, like salvation, ultimately spans the entire life of the believer. Initially, it is a work of grace subsequent to being justified, regenerated, or born again. It is an instantaneous work, which both sets one apart for God (1 Corinthians 1:2) and crucifies and cleanses the old nature, enabling the believer to be free from the dominant rule of sin: “Knowing this, that our old man is crucified with him, that the body of sin might be destroyed, that henceforth we should not serve sin. For, he that is dead is freed from sin” (Romans 6:6, 7). “And such were some of you: but ye are washed, but ye are sanctified, but ye are justified in the name of the Lord Jesus, and by the Spirit of our God” (1 Corinthians 6:11).
This dethroning of the old nature, this cleansing, this setting apart, places upon the believer the scriptural demand to “mortify the deeds of the body” through the Spirit (Romans 8:12, 13) and to “Mortify therefore your members which are upon the earth; fornication [sexual immorality], uncleanness, inordinate [abnormal] affection, evil concupiscence [desire for earthly things], and covetousness, which is idolatry” (Colossians 3:5). Second Peter 3:17, 18 further encourages growth in God’s grace and in the knowledge of Jesus Christ: “Ye therefore, beloved, seeing ye know these things before, beware lest ye also, being led away with the error of the wicked, fall from your own steadfastness. But grow in grace, and in the knowledge of our Lord and Saviour Jesus Christ. To him be glory both now and for ever. Amen.”
There is then in sanctification, a responsibility on the part of the believer to “put off” some habits and practices, and to “put on” others, which means there must be intentionality to holiness (Ephesians 4:22–32). Sanctification empowers us against sin’s control; the believer responds with a renewed mind to be transformed into the image of Christ (Romans 12:1, 2) and to be holy in life and conduct (2 Corinthians 7:1).