God’s saving grace in Christ is much bigger and more comprehensive than one might initially think. God’s grace not only rescues, it renovates. It not only justifies, it sanctifies. It not only reconciles, it renews. It not only propitiates, it purifies. It not only delivers, it matures. Indeed, the sovereign grace of God not only saves us from our sins, it saves us to a life of growing holiness. In these statements we are led to consider the biblical doctrine of sanctification, a central but often neglected facet of the life-changing gospel of grace. The following are five brief points that constitute the nuts and bolts of sanctification.
Sanctification is a Work of God’s Sovereign Grace
We know that God, by sovereign grace, regenerates (Eph. 2:4-5; I Pet. 1:3), justifies (Rom. 3:24), and adopts (Rom. 8:15-16; Gal. 4:4-7) guilty sinners through faith. But who does the sanctifying? Is it left up to us? The Bible teaches that God is the author and finisher of our sanctification (Phil. 1:6; I Thess. 5:24). Sanctification is a work of God’s free grace, and not a work of the believer’s autonomous moral strivings (c.f. WSC Q.35). We do not perfect “by the flesh” what was begun “in the Spirit” (Gal. 3:3). Just as a sinner cannot justify himself, so also he cannot sanctify himself. Sanctification is a work of God. Christ promises to sanctify his bride, the church (Eph. 5:26). He is faithful, and he will surely do it (I Thess. 5:24). Of course, sanctification, while a work of God, is not devoid of Spirit-empowered effort on the part of the believer. 
Sanctification is a Saving Benefit of Union with Christ
Union with Christ is at the very heart of the gospel, and there are many wonderful saving benefits that flow from a believer’s union with Christ. Indeed, when a person is united to Christ they are brought from spiritual death to spiritual life (regeneration), pardoned for sins and accounted righteous, solely on the grounds of the saving work of Christ (justification), and accepted into the beloved as sons and inheritors of eternal life (adoption, glorification). What we sometimes overlook or deemphasize, however, is that sanctification is also a benefit of union with Christ. A life of growth in grace is not merely a strongly suggested option for believers, it is the Spirit-wrought fruit of union with Christ.
As Christians, we should not only rejoice in our legal status before God (justification), but also the life-transforming relationship we have with God (sanctification). Christ, our living head, transforms the lives of his members (Rom. 5:18 – 6:14). Christ, the true vine, nourishes his branches (John 15:4-5). United to the perfect image of God, we are conformed more and more into his image (Rom. 8:29). Therefore, one cannot be united to Christ and remain the same (I Cor. 6:11; Eph. 2:1-10). God justifies and sanctifies sinners by grace through faith in Christ.
It is important to note the difference between justification and sanctification. Whereas justification is the once-for-all declaration that addresses our profound guilt and alienation, progressive sanctification is the ongoing process that destroys the remaining corruption of sin in us and increases the fruit of righteousness (Rom. 5:1-2; 8:12-14; Phil.1:9-11; WLC Q. 77). Justification and sanctification are distinct, but inseparable benefits of union with Christ (Duplex gratia). We never have one without the other. To negotiate or confuse either one of these central doctrines is to compromise the gospel.
Sanctification is both definitive and progressive
The grammar of God’s Word teaches us that believers are sanctified (definitive sanctification), and are presently being sanctified (progressive sanctification). We have been set apart as holy(I Cor. 1:2), and are thus called to be holy (I Pet. 1:14-16; Col.3:1-17). God has definitively sanctified us so that he might progressively sanctify us. Indeed, united to Christ, we have been set apart for sanctification. These important distinctions underscore the nature of our identity as God’s redeemed children, as well as the way in which we are called to live as his sons and daughters (I Peter 2:9-25).
In definitive sanctification we are called out, separated, and set apart from the world untoGod. Like the vessels in the temple which were set apart or sanctified for a holy purpose, so we who are in Christ Jesus have been set apart or sanctified for a holy purpose (2 Tim. 2:21). In this sense, God’s people are sanctified.
In progressive sanctification, the indwelling Holy Spirit transforms and renews the moral life of the believer. This inward renovation and spiritual growth impacts the whole man. The mind, heart, will, and affections are all progressively sanctified through the work of the Holy Spirit and the divinely appointed means of grace. The grace of sanctification renovates everything that sin has ruined. It is a complete renovation that occurs over a lifetime. Thomas Boston illustrates:
As the sap conveyed from the stock into the branch goes through it, and through every part of it; so the Spirit of Christ sanctifies the whole man. The poison of sin was diffused through the whole spirit, soul, and body of the man; and sanctifying grace pursues it into every corner (I Thess. 5:23). Every part of the man is sanctified, though no part is perfectly so. 
Just as a real estate investor might purchase ramshackle homes in a promising part of town, and over time renovate them to the highest standard; so God purchases ruined sinners with the blood of Christ, declares them his own, and over time renovates them to the highest standard, that is, the standard of Jesus Christ (Rom. 8:29).
This is good news! God’s grace not only saves, it sanctifies. It not only redeems, it renovates. We are not left to wallow in our sin as believers. No, God has called and empowered us to “grow in the grace and knowledge of our Lord and Savior Jesus Christ” and to mature in him (II Pet. 3:18; Eph. 4:13-16). We have been set free from the tyranny of sin to a life of increasing holiness. Of course, progressive sanctification is a life-long process. An oak tree doesn’t grow overnight. It takes years and decades to grow deep and abiding roots. As we earnestly seek the Lord, and encourage others to do the same, we must be prayerful and patient. A mentor of mine used to say, “we are sinners under construction.”
If you are in Christ, you have been sanctified to a life of growing godliness. United to Christ, you are set apart to a life of spiritual growth. Therefore, let us cut out of our lives that which would hinder spiritual progress, and cultivate those godly habits of devotion that would encourage it. Indeed, as “God’s chosen ones, holy and beloved” let us “put to death what is earthly” in us, and “put on” that which is pleasing to the Lord (Col. 3:12, 5, 12-17).
Sanctification is fostered through the Means of Grace
God, in his sovereign wisdom, appointed specific and objective means by which he saves, nourishes, grows, and matures his children spiritually (Acts 2:42). Those primary means of grace are the Word of God, sacraments, and prayer (I Cor. 1:18; Heb. 4:12; I Cor. 10:16-17; I Pet. 3:21; Mt. 6:5-15). When faithfully discharged, these ordinary means effectually communicate Christ and His saving benefits to God’s elect through the instrument of faith. In other words, they work. They are effectual. They accomplish that for which God purposed them (Is. 55:10-11). The Westminster Larger Catechism (1647) states:
Q. 154. What are the outward means whereby Christ communicates to us the benefits of his mediation?
A. The outward and ordinary means whereby Christ communicates to his church the benefits of his mediation, are all his ordinances; especially the Word, sacraments, and prayer; all which are made effectual to the elect for their salvation.”
The means of grace may be unimpressive, even foolish, to the onlooking world. Indeed, they have almost no marketing appeal in our glossy consumeristic age. Nevertheless, they are “the power and wisdom of God” (I Cor. 1:18-30).
Immediately following Pentecost, the early church was “devoted to the apostles’ teaching and the fellowship, to the breaking of bread and the prayers” (Acts 2:42). Why were they so passionately committed to these means? Why not something else? It was because they believed that through the Word, sacraments, and prayer that God’s eternal Kingdom is breaking into this broken world and saving lost sinners (Mt. 4:17). Christ is building his Church with his appointed tools–– the means of grace.
God’s inspired Word creates and nourishes true saving faith. Paul writes in Romans 10:17 that “faith comes from hearing, and hearing through the word of Christ.” We read elsewhere that, “like newborn infants [we are to] long for the pure spiritual milk, that by it we may grow up into salvation” (I Pet. 2:2). Again, faith is created and strengthened by the living Word of God. The Word raises us from spiritual death to spiritual life in Christ, and then nourishes our new life in him in order that we would grow and mature as God’s children (Eph. 2:5-6; 4:17-32). Christians are never meant to be stagnant. Quite the contrary. Those who have new life in Christ will be sanctified through the Spirit’s use and application of the law and promises of God’s Word (Heb. 4:12; II Tim. 3:16-17; Jn 17:17; Ps. 119). God’s law not only exposes sin and shows us our great need of Christ, it also serves as a sure guide for the Christian life.
The sacraments of baptism and the Lord’s Supper are also primary means of our sanctification in Christ Jesus. Through the waters of baptism and the elements of bread and wine at the table, God’s gospel promises are represented and confirmed to the faith of the believer. This visible word instructs the believer to look away from himself to the only true remedy for our sin and misery–– the cleansing blood of Jesus (Titus 3:5; Mt.26:26-29). Rightly understood, then, baptism and the Lord’s Supper firmly “fix our eyes on Jesus Christ, the founder and perfecter of our faith” (Heb. 12:2). Again, notice that Christ not only creates faith, he strengthens it (sanctification); and he does so through his ordained means of Word, sacraments, and prayer. The sacraments not only remind us that we are justified, but also that we are being sanctified. With grateful hearts and eyes fixed on the crucified and risen Christ, believers pursue a life of growing faith and godliness.
Prayer is also a means by which God sanctifies his redeemed children. As we pray according to God’s will, the Holy Spirit uses those prayers to transform our hearts and lives, and the hearts and lives of others for whom we pray. The Heidelberg Catechism states that “God will give his grace and Holy Spirit to those only, who with sincere desires continually ask them of Him, and are thankful for them” (HC Q. 116). Prayer doesn’t change God, it changes us. God uses it to transform his people.
Sanctification Requires Spirit-empowered Effort and Discipline
The Apostle Paul exhorted the first century believers in Philippi to “work out [their] salvation with fear and trembling,” recognizing that “it is God who works in [them], both to will and to work for his good pleasure” (Phil. 2:12b-13). In other words, by the power of God’s indwelling Spirit, Christians are called to work out what God works in. Sanctification takes Spirit-empowered effort and discipline. RC Sproul writes that “Sanctification is a lifelong process that involves an enormous amount of intensive labor.”  Indeed, spiritual growth is no stroll in the park. Indeed, Paul charges Timothy to
“train [himself] for godliness, for while bodily training is of some value, godliness is of value in every way, as it holds promise for the present life and the life to come. For to this end we toil and strive, because we have set our hope on the living God” (I Tim. 4:7b-10a).
The Scriptures describe the Christian life as a fight (I Tim. 6:12), a race (II Tim. 4:7), a toil and striving (I Tim.4:7b-10a), and a war (Eph. 6:10ff). Saved by the grace of Christ and set free from the tyranny of sin (Rom. 8:2), we are called to “forget what lies behind and strain forward to what lies ahead, [and] press on toward the goal” (Phil. 3:13b-14). Therefore, Kevin DeYoung is right when he states that “it is the consistent witness of the New Testament that growth in godliness requires exertion on the part of the believer.”
According to Scripture and the Reformed Confession, the believer’s Spirit-empowered effort in sanctification consists of mortification and vivification; that is, an active killing of remaining indwelling sin and an active pursuit of the marks of godliness. The Westminster Confession of Faith explains that:
They, who are once effectually called, and regenerated, having a new heart, and a new spirit created in them, are further sanctified, really and personally, through the virtue of Christ’s death and resurrection, by his Word and Spirit dwelling in them: the dominion of the whole body of sin is destroyed, and the several lusts thereof are more and more weakened and mortified; and they more and more quickened and strengthened in all saving graces, to the practice of true holiness, without which no man shall see the Lord. 
In Christ we have been set free from the reign of sin and death, and have become “slaves of righteousness leading to sanctification” (Rom. 6:17-19). Notice that our sanctification or growth in grace consists of both a dying unto sin and a living unto God. Sanctification is putting off indwelling sin, and putting on sincere godliness (Col. 3:1-17)–– a purging of remaining corruption and a cultivation of growing holiness. Christians are strongly exhorted to
“put off your old self, which belongs to your former manner of life and is corrupt through deceitful desires, and to be renewed in the spirit of your minds, and to put on the new self, created after the likeness of God in true righteousness and holiness (Eph. 4:22-24).
The framers of the Westminster Confession describe this process of sanctification as happening “more and more” over the course of a lifetime. Therefore, on this side of heaven there will always be a “continual and irreconcilable war” with indwelling sin and fierce temptation.  Even so, like Paul, we can be sure that “he who began a good work in you will bring it to completion at the day of Christ Jesus” (Phil. 1:6; Rom. 7:24-25).
Over the last 15-20 years there has been a valiant effort to recover the gospel of grace in the evangelical world, especially as it concerns the doctrine of justification. Myriad conferences, coalitions, books, and articles have been dedicated to answering the question: How can a guilty sinner be reconciled to a holy God? To be sure, there is still much work to be done on this front. There always will be. Even so, we are grateful for the strides that have been made. Less of a focus, it could be argued, has been placed on the doctrine of sanctification. At the risk of being anecdotal, a quick survey of the publishing and conference world over the past decade or so will reveal a lack of attention to this crucial tenet of the gospel. Again, we must understand that our union with Christ in his death and resurrection speaks not only to our justification, but also to our sanctification (Rom. 6:1-14). William Perkins comments:
“We must not only know and believe that Christ died for our sins and rose for our justification, but we must labor to feel the power and efficacy of His death, killing sin in us, and the virtue of his resurrection, raising us up to newness of life. He that has only a show of religion may make profession of faith in Christ’s death and resurrection, but herein stands the power, when we be made conformable to His death in regard of the death of sin, and know the virtue of His resurrection by our holy endeavor in new obedience, and do frame ourselves to His example in all such things wherein He left Himself a pattern unto us.” 
Christ’s death and resurrection are efficacious to both save and sanctify his people. Declared righteous and adopted as sons, Christians are called to actively live as “obedient children … not conformed to the passions of [our] former ignorance, but as he who called you is holy, you also be holy in all your conduct, since it is written, ‘You shall be holy, for I am holy’” (I Pet. 1:14-16). Understood correctly, then, this call to grateful obedience in no way undermines, threatens, diminishes, or compromises the gospel. It is not legalism. Rather, it is the fruit that adorns the lives of those who are united to Christ and abide in him (John 15:4; Gal. 5:22-23; WCF 19.7). God sanctifies his redeemed children. By doing so he prepares us for glory. Watson notes: “As you first cleanse the vessel, and then pour in the wine; so God first cleanses us by sanctification, and then pours in the wine of glory.” 
When a person is united to the living and exalted Christ, things change. A lifelong, supernatural work of spiritual transformation begins, a Spirit-enabled process called sanctification. It is a work of free grace, and thus reflects the bigness of God’s saving love. Let us seek to recover a robust, biblical, and Reformed doctrine of sanctification for our lives, families, and churches.
 Thomas Boston, Human Nature In It’s Fourfold State, 294-295.
 RC Sproul, Everyone’s A Theologian, 249.
 Kevin DeYoung, The Hole In Our Holiness, 88.
 Westminster Confession of Faith, 13.1.
 Ibid., 13.2
 William Perkins, The Works of William Perkins, Vol. 1, 490-491–– emphasis mine.
 Thomas Watson, A Body of Divinity, 248-249.