Through union with Christ, you are righteous (having been justified), new (regenerated), and holy (definitively sanctified). In this unbreakable union with Christ we are given a new history, a new identity, and a new destiny.
• We are given a new history, because his past counts as our past: his perfect life and obedient death is credited as ours. His death to the ruling power of sin counts as ours, securing our freedom from sin’s tyranny.
• We are given a new identity, because when we are joined to Christ, God sees us in his Son. In fact, we become saints, children of God, and heirs with Christ.
• We are given a new destiny, because in the resurrection of Christ, the age to come has dawned. His resurrection guarantees that we will be raised from the dead as well, and, in fact, empowers us to live in newness of life in the here and now.
Jesus has not just given us a ticket to heaven. He has changed our essential identity. He has irrevocably altered the effect of our past on our present and future by causing his death and resurrection to count as ours. We really are new creatures, even as we press on by God’s grace to become more holy.
The point is that sanctification (freedom from the dominion of sin), no less than justification (freedom from the guilt of sin), comes through faith in Christ alone. Everything we need for life and godliness is found in him! Transformation can happen in no other way.
The gospel reminds us that Christ himself is the one and only human being who has perfectly imaged the holy character of God. He is the pioneer of our salvation, the new Adam, and therefore, the head of the new creation. We can only reflect the image of God as we become like Christ. And we can only become like him if we are in him. As Sinclair Ferguson rightly says,
Perfect humanity, perfect holiness, is first of all expressed in him . . . The nature of sanctification is that it is true God-likeness. But true God-likeness in human form is Christ-likeness. Since Christ-likeness is the full expression of the image of God in man, true sanctification is true humanness. The only resources for such sanctification are in Christ. Our sanctification is Christ’s sanctification of himself in our humanity progressively applied to and realized in us through the ministry of the Holy Spirit . . . Sanctification can be ours only by means of the resources of Christ, brought to us through the Holy Spirit as he takes what is Christ’s, reveals it to us, and thus conforms us more and more into his likeness, from one degree of glory to another, as we gaze on the glory of the Lord (2 Cor. 3:18).
You and I will experience deep and lasting change only as the Holy Spirit applies the resources of the gospel to our hearts and lives. The gospel tells us that we are already freed from sin as a ruling power. The gospel also points us to Christ as the pattern for holiness; he is the quintessentially sanctified human being. And the gospel promises that the riches of Christ, applied to our hearts, will effectively produce progressive change in our lives.
-excerpt from Brian Hedges excellent book - Christ Formed in You