Most Christians misunderstand their justification, and it severely robs them of joy and causes them to unnecessarily stumble through doubt, fear, and sin. Yet, an appropriate understanding of justification actually fuels our growth in godliness as we see the truths of the gospel applied to our lives.
Richard Lovelace accurately describes the way that most Christians misunderstand the doctrine of justification:
“Only a fraction of the present body of professing Christians are solidly appropriating the justifying work of Christ in their lives. Many have so light an apprehension of God’s holiness and of the extent and guilt of their sin that consciously they see little need for justification, although below the surface of their lives they are deeply guilt-ridden and insecure. Many others have a theoretical commitment to this doctrine, but in their day-to-day existence they rely on their sanctification for justification, in the Augustinian manner, drawing their assurance of acceptance with God from their sincerity, their past experience of conversion, their recent religious performance or the relative infrequency of their conscious, willful disobedience. Few know enough to start each day with a thoroughgoing stand upon Luther’s platform: you are accepted, looking outward in faith and claiming the wholly alien righteousness of Christ as the only ground for acceptance, relaxing in that quality of trust which will produce increasing sanctification as faith is active in love and gratitude.”
The bottom-line reality of justification is that we are “accepted before God because of who Christ is and what He has done.” Our faith in Christ secures our right-standing before God and empowers us to be transformed into His likeness.
Justification provides the fuel on which the vehicle of sanctification runs: God declaring us righteous by status, is the grounds on which the Spirit transforms us to be righteous in behavior. Michael Reeves provides a more helpful, illustrative example of this truth in terms of Christ uniting himself in marriage to an undeserving prostitute (the Church): You can read it here!! It is the love of Christ that changes us to eventually display a lifestyle that is worthy of such love. It is not our love for Him that changes us–our default is to be lovers of self and lovers of sin. He loved us first, when we refused to love Him, and such sacrificial love begins to change us until we begin to love Him in return. In other words, Christ’s union with us is motivated by His deep love for us (not because of our worthiness of being loved by Him), and in the security of His faithful love (despite our occasional affair with sin) we begin to respond to Him with a similar, though imperfect love. And one day, when we see Him face to face, we shall be like Him (1 John 3:2).
The reason we can be confident in Christ’s faithful love for us is displayed in the Cross. He went to the Cross in order to stand in our place. His life provided the obedience that we could never adequately obtain, and His death experienced the condemnation that we so rightfully deserved. In other words, He became our substitute in every way–He became our righteousness before God and He became our curse before God; He experienced God’s wrath for our sin. As Luther so aptly said it, “He is my righteousness, and I am His sin.” We have nothing to bring to God except for our sin–and yet, Jesus provides every ounce of righteousness that we need in order to be justified before God (2 Cor. 5:21). By putting our faith in Christ as our Substitute, we receive all the blessings of justification. (Here you can read a brief elaboration regarding Christ’s substitution as “the heart of the gospel”.)
Sanctification, on the other hand, is the outworking of our justification. It might be rightly summarized as “justification applied.” As God applies the truths of the gospel (Christ’s work on our behalf), we experience the transforming power of the Holy Spirit. As we worship Christ, the Holy Spirit transforms us into His image from one degree of glory to another (2 Cor. 3:18; Rom. 8:21-39). He enables us to display the fruit of Christlikeness (Gal. 5:16-26) and empowers us to say no to ungodliness (Titus 2:11-14). However, this process of transformation is progressive–meaning, that it doesn’t happen all at once. It happens in degrees and throughout seasons of life, until we reach maturity. There will be set-backs, as well as giant leaps forward; however, most of the time we experience such slow growth that we can sometimes feel discouraged or doubt our own salvation and/or maturity. In fact, John Piper has often remarked of being most in doubt of his own salvation when he sees how painfully slow his sanctification actually is. The reality is that our sanctification is a spiritual battle that is won inch-by-inch as we entrust ourselves to the One who fights our battles for us. While we should “work out our salvation with fear and trembling,” we realize that it is “God who works in us to will and to work for His own good pleasure” (Philippians 2:12-13). We should pursue Christlikeness in humility and faith and God-centered worship, but realize that it is God who gives us the motivation and ability to actually change. And, He who began a good work in us will bring it to completion when He comes again to consummate His union with us (Phil. 1:6). In other words, we are pieces of fruit that are ever-growing in maturity until Christ returns and finally makes us completely ripe and sweet.
Misunderstanding our justification can be detrimental to our growth in godliness–it can lead to minimizing our sin or the holiness of God, and thereby rendering the cross of Christ as seemingly unnecessary. Or we think that our standing before God is dependent on how well we live our lives–the quality of our devotions, the sincerity and consistency of our love for God, the frequency of our victory over sin, etc. And while all of these things are important features of our spiritual maturity (sanctification), they are not the grounds for our ability to stand “guilt-free” before God (justification). Christ bore our shame and provided to us His guilt-free life, and through our worship of Him, the Holy Spirit makes our lives increasingly reflect His character. Therefore, we should wake up everyday with the realization that we are righteous before God (due to faith in Christ who secured our justification) and that our greatest need is to continually worship God in humility, gratitude, and faith for the work that He has already done, continues to do, and has promised to complete for us, in us, and through us. He has defeated our sin and will one day put an end to it. In the meantime, we strive–by His power–to live by faith, to hope in His promises, to battle our sin, to love others, and to display the fruit of His Spirit as we perform the good, God-honoring deeds that He has prepared in advance for us to do (Eph. 2:1-10).
We must not confuse justification and sanctification. In the worst case, a confusion of these matters may result in false assurance for those who think they are saved, yet are actually headed toward hell: those who trust in their works to make them right before God. In the better case, a confusion of these matters would make the true believer live a life full of unnecessary guilt and doubt regarding his own salvation due to his/her struggles to be Christlike: these believers can only be free of the burden when they realize that Christ has already stood in their place and they simply need to worship Him by faith as He completes everything that He has started on their behalf. In order to see sanctification rightly, we must have a functional understanding of justification. In other words, the truths of our justification should be connected to our everyday lives (i.e., living guilt free, responding to Christ by faith, trusting in God’s promises, asking God to finish the work that He started, confessing sin yet believing that we are forgiven and clean before Him, trusting in the Holy Spirit to strengthen us and change us, etc). Here, John Piper offers a brief summary of the difference between justification and sanctification!
It is only when we rest in the righteousness of Christ that we begin to reflect Him. As we recognize that God accepts us as we are—because of Christ—and that He intends to change us to reflect His Son—because of the Holy Spirit, we then begin to live the life of faith that is free of guilt and is fertile for gospel transformation to take place. May we live in such a way…
 Richard Lovelace, Dynamics of Spiritual Renewal (Downers Grove: IVP, 1979), 101.
 See Ray Ortlund, Jr. on the differences between justification and self-justification: here.