The words justification and sanctification have largely fallen out of use in Western culture. Sadly, they are also fading from sight in the Christian church. One reason this decline is distressing is that the Bible uses the words justification and sanctification to express the saving work of Christ for sinners. That is to say, both terms lie at the heart of the biblical gospel. So, what does the Bible teach about justification and sanctification? How do they differ from one another? How do they help us understand better the believer's relationship with Jesus Christ?
Justification is as simple as A-B-C-D. Justification is an act of God. It does not describe the way that God inwardly renews and changes a person. It is, rather, a legal declaration in which God pardons the sinner of all his sins and accepts and accounts the sinner as righteous in His sight. God declares the sinner righteous at the very moment that the sinner puts his trust in Jesus Christ (Rom. 3:21-26, 5:16; 2 Cor. 5:21).
What is the basis of this legal verdict? God justifies the sinner solely on the basis of the obedience and death of His Son, our representative, Jesus Christ. Christ's perfect obedience and full satisfaction for sin are the only ground upon which God declares the sinner righteous (Rom. 5:18-19; Gal. 3:13; Eph. 1:7; Phil. 2:8). We are not justified by our own works; we are justified solely on the basis of Christ's work on our behalf. This righteousness is imputed to the sinner. In other words, in justification, God puts the righteousness of His Son onto the sinner's account. Just as my sins were transferred to, or laid upon, Christ at the cross, so also His righteousness is reckoned to me (2 Cor. 5:21).
By what means is the sinner justified? Sinners are justified through faith alone when they confess their trust in Christ. We are not justified because of any good that we have done, are doing, or will do. Faith is the only instrument of justification. Faith adds nothing to what Christ has done for us in justification. Faith merely receives the righteousness of Jesus Christ offered in the gospel (Rom. 4:4-5).
Finally, saving faith must demonstrate itself to be the genuine article by producing good works. It is possible to profess saving faith but not possess saving faith (James 2:14-25). What distinguishes true faith from a mere claim to faith is the presence of good works (Gal. 5:6). We are in no way justified by our good works. But no one may consider himself to be a justified person unless he sees in his life the fruit and evidence of justifying faith; that is, good works.
Both justification and sanctification are graces of the gospel; they always accompany one another; and they deal with the sinner's sin. But they differ in some important ways. First, whereas justification addresses the guilt of our sin, sanctification addresses the dominion and corruption of sin in our lives. Justification is God's declaring the sinner righteous; sanctification is God's renewing and transforming our whole persons—our minds, wills, affections, and behaviors. United to Jesus Christ in His death and resurrection and indwelt by the Spirit of Christ, we are dead to the reign of sin and alive to righteousness (Rom. 6:1-23; 8:1-11). We therefore are obligated to put sin to death and to present our "members to God as instruments for righteousness" (6:13; see 8:13).
Second, our justification is a complete and finished act. Justification means that every believer is completely and finally freed from condemnation and the wrath of God (Rom. 8:1, 33-34; Col. 2:13b-14). Sanctification, however, is an ongoing and progressive work in our lives. Although every believer is brought out once and for all from bondage to sin, we are not immediately made perfect. We will not be completely freed from sin until we receive our resurrection bodies at the last day.
Christ has won both justification and sanctification for His people. Both graces are the concern of faith in Jesus Christ, but in different ways. In justification, our faith results in our being forgiven, accepted, and accounted righteous in God's sight. In sanctification, that same faith actively and eagerly takes up all the commands that Christ has given the believer. We dare not separate or conflate justification and sanctification. We do distinguish them. And, in both graces, we enter into the richness and joy of communion with Christ through faith in Him.