Interestingly, the theological traditions within Christendom have differing ideas about how sanctification comes about in the life of the believer. For example, even within evangelicalism some groups (such as the Holiness, Nazarene, and Pentecostal traditions) view sanctification as happening through spiritual crisis events and resulting in complete moral perfection, whereas other groups (such as the Lutheran, Reformed, and Anglican traditions) view it as a lifelong continual process that never reaches perfection in this life. My own studies in Scripture and in theology as well as in life experience persuade me that the latter view is closer to the truth, but I nevertheless can respect other traditions that understand the issue differently.
Two Views of Sanctification
I have long been associated with theological traditions that seem to me to talk a lot more about grace, faith, and justification than they did about repentance, good works, and sanctification. I'm not criticizing that perspective because I think an understanding of the depth of God's grace is critical to understanding God's entire plan of salvation, including justification, sanctification, and even glorification. So God's grace (Greek: charis, or "unmerited favor") is the foundation for the entire Christian experience. Yet I think Scripture is crystal clear that the grace that saves us through faith in Christ also motivates us to pursue a godly life (see Titus 2:11–15).
I always appreciate being reminded that salvation is a free gift of God. But I wonder why the message of sanctification is sometimes given far less emphasis. My impression is that the importance of sanctification can be underemphasized because it is at times such a difficult process and we see so little growth in Christ that we feel rather defeated. At points like this we need to remind ourselves of Paul's incredible biblical promise: Nothing can "separate us from the love of God that is in Christ Jesus our Lord" (Romans 8:39).3 We need to realize that the Christian life with its everyday ups and downs can and should be lived by grace and in the critical understanding that God continually forgives and strengthens us for his service.
On the other hand, I have also talked with Christians of other traditions who greatly emphasize the living of the Christian life. These believers rightly affirm that the believer in Christ is a new creation in Christ Jesus (2 Corinthians 5:17). I appreciate their emphasis that God can and does transform the lives of his people and that Scripture implores believers to take sanctification very seriously (2 Corinthians 7:1; Galatians 5:24). These believers like to emphasize that grace is also a power that can serve to change the lives of believers.
I am greatly encouraged to know that I am not only saved by grace but that I can also live by grace and be empowered by God to resist sin. Yet I wonder if it is not also possible to exaggerate one's level of sanctification because we are often oblivious to the depth of our sin even as Christians. For example, try giving up being selfish just for a day or two—it's impossible! So some, or a lot, of what St. Augustine and Martin Luther called incurvatus in se (Latin: "curved in on oneself," meaning inner selfishness) remains long after our conversion to Christ.
I think Luther's famous statement in Latin: simul justus et peccator (“simultaneously righteous and sinful”) reflects both Scripture and our own experience. In our standing before God we have been declared forgiven and granted the imputed righteousness of Christ, or justification (Romans 5:1); yet in our present state we remain sinners. We have been forever changed but we still sin. So I think it best to consider ourselves after the new birth as "forgiven sinners."
Here is a definition of sanctification that I recently came across that I think is realistic but still hopeful: