In the previous chapters, we have witnessed the legal wonder of Justification (where God declares us righteous) and the relational warmth of Adoption (where God makes us sons). But a critical question remains: Does God simply hand us a ticket to heaven and leave us in our filth? Does He change our status without changing our nature?
Chapter 13 answers with a resounding “No.” It introduces the doctrine of Sanctification. Justification frees us from the penalty of sin; Sanctification frees us from the power and pollution of sin. It is the process by which the Holy Spirit takes the “new heart” given in regeneration and works it out into every corner of our lives, making us actually, practically holy.
The Confession teaches that those who are regenerated are further sanctified by God’s Word and Spirit; that this work destroys the dominion of sin and strengthens saving graces; that it is imperfect in this life, leading to a continual war between flesh and Spirit; yet, through the supply of the Spirit, the believer will inevitably grow in grace.
The Divine Operation (WCF 13.1)
The Confession defines Sanctification as a work that happens to those “who are effectually called, and regenerated.” It is the necessary fruit of the New Birth. This work is described as “real and personal.” It is not merely a change in standing (like Justification), but a change in being.
How does this happen? The divines trace the power source directly to the cross: “through the virtue of Christ’s death and resurrection.” The same power that raised Jesus from the dead is at work in the believer to kill sin and raise them to new life (Rom. 6:4–6).
This involves two distinct movements:
- Mortification: “The dominion of the whole body of sin is destroyed, and the several lusts thereof are more and more weakened and mortified.”
- Vivification: They are “more and more quickened and strengthened in all saving graces, to the practice of true holiness.”
The necessity of this work is stark: “without which no man shall see the Lord” (Heb. 12:14). Heaven is a holy place for a holy people; if we have no taste for holiness here, we would have no joy there.
A Monergistic Work of Grace
There is a common misunderstanding that while Justification is by faith alone, Sanctification is by “faith plus works”—that God gets us started, but we must finish the job by our own bootstraps. This view turns the Christian life into a cooperative partnership where God does His part and we do ours.
However, the Westminster Standards point us in a different direction. Notice the language of the Westminster Larger Catechism, Question 75. It defines Sanctification as “a work of God’s grace, whereby they… are in time, through the powerful operation of his Spirit… renewed in their whole man.”
Sanctification is fundamentally monergistic (one worker). It is God’s work. It is the “powerful operation of his Spirit” that renews us. To be sure, we are active—we strive, we fight, we obey—but our acting is the result of God’s acting, not the cause of it. As Paul writes in Philippians 2:13, “For it is God who works in you, both to will and to work for his good pleasure.” We work because He is at work. We do not sanctify ourselves with God’s help; God sanctifies us, mobilizing our wills and affections in the process.
The War Within (WCF 13.2)
If God is the one sanctifying us, why are we not perfect instantly? The Confession explains that “this sanctification is throughout, in the whole man… yet imperfect in this life.”
Every part of us is touched by grace (mind, will, affections), but every part is still infected by “remnants of corruption.” This creates the normal Christian life: “a continual and irreconcilable war, the flesh lusting against the Spirit, and the Spirit against the flesh” (Gal. 5:17).
This is a comfort to the weary saint. The presence of struggle is not a sign that you are lost; it is a sign that you are alive. Dead bodies don’t fight. The very fact that you hate your sin and struggle against it is evidence that the Spirit of holiness has set up camp in your heart and is waging war against the old regime.
Victory Assured (WCF 13.3)
The battle is fierce, and the Confession admits that “the remaining corruption, for a time, may much prevail.” There are seasons where a believer may slide backward, stumble, or seem overcome by a besetting sin.
But the final outcome is not in doubt. Why? Not because of the strength of our will, but “through the continual supply of strength from the sanctifying Spirit of Christ.” Because it is God’s work, it cannot fail. The regenerate part “doth overcome.” We “grow in grace, perfecting holiness in the fear of God.”
Sanctification is not a straight line upward; it is often a jagged graph with valleys and peaks. But the trajectory is set. He who began a good work in you will bring it to completion (Phil. 1:6). We fight with the confidence of soldiers who know the war has already been won.
Key Terms
- Sanctification: The work of God’s free grace, whereby we are renewed in the whole man after the image of God, and are enabled more and more to die unto sin, and live unto righteousness.
- Mortification: The aspect of sanctification involving the killing of sin, weakening its power and destroying its dominion in the life of the believer.
- Vivification: The aspect of sanctification involving the making alive of the new man, strengthening the believer in the practice of true holiness.
- Definitive Sanctification: The initial break with the power of sin that occurs at regeneration (noted in “dominion… is destroyed”).
- Progressive Sanctification: The ongoing, lifelong process of becoming more holy (noted in “more and more weakened… more and more quickened”).