What Is Sanctification? A Biblical Definition

Sanctification has both an individual and a corporate dimension for Christians, a present and an ultimate meaning. However, this is not the way that sanctification is commonly defined or understood in many evangelical circles today.

Bruce Milne puts it this way:

Having brought us to birth “in Christ,” the Spirit continues to work upon us to conform us more and more to the image of the Christ with whom he has united us. This process of moral renewal and transformation is commonly referred to as sanctification.¹

Milne acknowledges that the root idea of “sanctify” is to “set apart” or “consecrate” people to be God’s own possession. But he argues that this terminology has a second meaning in Scripture, a meaning “which now prevails in theological usage: the attainment of intrinsic holiness of character” (Lev 11:44–45; 1 Thess 4:3; 5:23; cf. 2 Cor 3:17–18).² This change of emphasis is significant, because it takes the focus away from the definitive work of Christ for his people collectively. Instead, it concentrates on the issue of progress in the Christian life. The NT has other terms for this progress, such as “transformation,” “renewal,” and “growth.”³

Milne goes on to say:

Scripture’s lack of a single term to refer to the growth in holiness of God’s people, and its use of a term rooted in the once-for-all status we receive in faith-union with Christ, underline the impossibility of separating the crisis of renewal from subsequent moral transformation. In theological terms, justification (a once-for-all act affording the Christian righteous standing before God) cannot be separated from sanctification (the life-long process of moral transformation into more of Christ’s image).⁴

Milne rightly insists that “The Spirit’s ministry in sanctification must be understood from the perspective of the fundamental, indissoluble relationship between Christ and the Spirit,” but he fails to show how the Bible’s emphasis on definitive or positional sanctification should motivate and inspire us to godly living and maturation in Christ. The issue is not simply terminological, but hermeneutical and pastoral.

Sanctification in the Old Testament

The discipline of biblical theology teaches us to examine carefully the foundations of NT teaching in the OT, looking for points of continuity and points of discontinuity. This is especially necessary when seeking to understand the nature of sanctification for New Covenant believers.⁵ The root meaning of the Hebrew words for holiness and sanctification is hard to determine etymologically, but “set apart” is a valid inference, since the opposite is “profane” or “common” (Lev 10:10). Fundamentally, the terminology is used to describe “the essential nature that belongs to the sphere of God’s being or activity and that is distinct from the common or profane.”⁶

In fulfillment of his covenant promises to their ancestors, God undertook to free the Israelites from slavery in Egypt, to redeem them “with an outstretched arm and with mighty acts of judgment,” and to take them as his own people into the land he had sworn to give them (Exod 6:6–8). In Exodus 15:17, this land is described as “the place, LORD, you made for your dwelling, the sanctuary, Lord, your hands established.” In due course, having separated them from the Egyptians, he brought them to himself at Sinai (Exod 19:1–4) and declared:

Now if you obey me fully and keep my covenant, then out of all nations you will be my treasured possession. Although the whole earth is mine, you will be for me a kingdom of priests and a holy nation. (Exod 19:5–6)

The Lord effectively “sanctified” Israel by this means. A common factor in the terms describing Israel’s vocation is an emphasis on separation from the nations to be uniquely at God’s disposal. As “a holy nation,” they were to demonstrate what it meant to live under the direct rule of God, with his sanctifying presence in their midst (Deut 7–15). As “a priestly kingdom,” they were to serve the Lord exclusively and thus be a people through whom his character and will might be displayed to the world (Deut 16–26). In this way, God’s original promise to bring blessing to “all peoples on earth” would be enacted (Gen 12:3).⁷

A common factor in the terms describing Israel’s vocation is an emphasis on separation from the nations to be uniquely at God’s disposal.

After Sinai, the ritual provisions of the covenant were meant to sustain Israel as a distinctive people, set apart to serve God. Elaborate instructions were given for setting apart Aaron and his sons as priests (Exod 28), with Levites to assist them (Num 8:14–19). Both groups were consecrated to God from within Israel, so that the nation could remain a consecrated people and continue to draw near to God in his holiness (Exod 29:42–46). The tabernacle, and later the temple, represented God’s holy presence in the midst of his people and his rule over them. God’s sanctifying presence would continue to mark them as his own people and facilitate holiness of living as a response.

The demand of the law was not for progressive sanctification, but actualization of their holy status and relationship with God in daily obedience: “You shall be holy, for I am holy” (Lev 11:44–45; 19:2; 20:7, 26). By keeping God’s ritual, moral, and social laws, the people of Israel would not profane his holy name before the nations. Rather, they would demonstrate God’s character and the benefit of being “a people holy to the Lord,” chosen out of all the peoples on earth to be his “treasured possession” (Deut 14:2). Pollution and sin were to be avoided in every aspect of life, and there was to be a complete break with every form of idolatry and false religion. Separation from the nations and consecration to God were two different facets of their exclusive relationship with the Lord. When transgression occurred, rites of purification were available for the restoration of “cleanliness” and holiness.

Israel’s failure to be God’s holy people is described at length in the OT, especially in 1–2 Kings and the prophetic literature. God’s judgment was experienced through invasion and exile, first by the Assyrians and then by the Babylonians. But God promised to restore a remnant of the people to his holy place and renew his covenant with them (Ezek 36:24–32; cf. Jer 31:27–34). He would re-establish the Davidic kingship and his sanctuary or dwelling place among them forever (Ezek 37:24–28; cf. Isa 9:6–7). In this way, God would be “proved holy” through his people in the sight of the nations (Ezek 20:41; 36:22–23), thus fulfilling his original plan for them.

Sanctification in Christ

The sanctifying of the Son of God

Just as Israel was set apart by God’s saving activity in the time of Moses and in the restoration after the Babylonian exile to serve him and glorify him, so sanctification in the NT is achieved by a divine act. The Greek verb hagiazō (“set apart,” “sanctify,” “consecrate,” “make holy”) is first used in connection with Jesus’s role as “the one whom the Father set apart as his very own and sent into the world” (John 10:36). When he claims to sanctify himself “for their sakes” (17:19), he refers to his approaching death as “the Lamb of God who takes away the sin of the world” (1:29, 36) and as “the good shepherd” who “lays down his life for the sheep” (10:11, 17–18). The Messiah must die to deliver his people from God’s judgment (11:49–53) and make it possible for believers to be drawn to him from every nation (12:20–33). Disciples are separated from the world and from “the evil one” by being consecrated in “the truth” that Christ proclaims and lives out (17:15–17). This truth includes his teaching about the need for his sacrificial death. By this truth, we are set free to bring blessing to the world as his agents (17:18; cf. Gen 12:3). Jesus prays that we might be kept from being overwhelmed by the world and its values, so that we might be “truly sanctified” to the Father and his values (17:19).⁸

The notion that the Son of God is the great high priest whom the Father has sent into the world to offer himself as a perfect sacrifice for sin is made explicit in Hebrews 10:1–14. The Messiah took upon himself the task of fulfilling the plan of God described in Psalm 40:6–8. In the body that was “prepared for” him, he lived a life of perfect obedience to the Father, culminating in his death as an unblemished sacrifice for sins (Heb 4:15; 5:7–10; 7:26–27; 9:14; 10:12–14). He set aside the ancient sacrificial system by expressing the obedience that was always God’s intention. His complete self-consecration in death made possible a consecration of God’s people in a way that had not occurred before. By the will of the Father, revealed in Scripture and carried out by the Son, Hebrews proclaims that “we have been made holy through the offering of the body of Jesus Christ once for all” (10:10). The verb “made holy” points to a state or condition made possible for us by the self-offering of Jesus in death (ESV, CSB: “we have been sanctified”). The preceding context suggests that this involved a once-for-all cleansing from sin that the law of Moses could not provide (10:1–4). No further sacrifices or rituals are required to keep us in that sanctified condition.

Hebrews 10:11–18 indicates that the verb “make holy” or “sanctify” is primarily employed in a covenantal sense.⁹ Christ’s sacrifice definitively binds people to God in a new relationship of heart-obedience, fulfilling the promises of Jeremiah 31:31–34 (contrast Jer 9:13). The covenantal dimension is highlighted again in 10:29, when the author mentions “the blood of the covenant that sanctified them.” The ascended Lord Jesus is “the one who makes people holy” in this relational and covenantal sense, so that “those who are made holy are of the same family” (Heb 2:11). The author envisages a spiritual bond between the Son and those he consecrates, originating in the will and purpose of God (cf. Eph 1:3–4).¹⁰

The implications for believers

Sanctification in Christ has an inward as well as an outward aspect. The sacrifice of Christ makes possible a cleansing of consciences “from acts that lead to death, so that we may serve the living God” (Heb 9:14; cf. 10:22). When the message about his completed and eternally effective work is applied to the heart or conscience of believers, it brings an inner conviction of forgiveness, acceptance, commitment, and hope. A life of dedicated service or worship results (12:28–29). Consecration as a human response is made possible by God’s historic action through his Son: cleansing us from sin and consecrating us to himself for eternity (cf. 1 Pet 3:15, “in your hearts regard Christ the Lord as holy”).

Paul is not describing a sequence by which God justifies, sanctifies, and then redeems. Rather, he draws on three different but related strands of biblical thought to describe the same reality, namely our eternal status or standing with God through Jesus Christ.

The Apostle Paul similarly links sanctification with Christ’s justifying and redemptive work when he writes that the Messiah Jesus has “become for us wisdom from God—that is our righteousness, holiness and redemption” (1 Cor 1:30). Here the Greek noun hagiasmos (“holiness,” “sanctification”) is one of three explanations of how God has made Jesus the wisdom that leads to eternal salvation. Paul is not describing a sequence by which God justifies, sanctifies, and then redeems. Rather, he draws on three different but related strands of biblical thought to describe the same reality: namely, our eternal status or standing with God through Jesus Christ.¹¹

In the words of Roy Ciampa and Brian Rosner,

to be in Christ is to enjoy both a secure and objective status before God and a new mode of eschatological existence in solidarity with other believers.¹²

They further observe that

Righteousness recalls the law court and speaks of vindication and acquittal, holiness brings to mind the temple and being set apart for God, and redemption evokes the slave market and emancipation on the analogy of Israel’s deliverance in the exodus.¹³

Sanctification & holy living

Given the moral and spiritual problems that Paul discerned in the Church of Corinth, it may seem surprising that he addressed them as “those who are sanctified in Christ Jesus” (1 Cor 1:2). But this was part of his strategy for challenging their behavior. They were a holy and distinct people in that corrupt and godless city because God had drawn them into an exclusive relationship with himself through his Son. Paul’s expression should be understood as a way of speaking about their conversion and incorporation into Christ, when the Holy Spirit enabled them to believe the gospel (cf. 2 Thess 2:13–14; Eph 5:25–27; Rom 15:16; Acts 20:32; 26:18; 1 Pet 1:2). But they needed to express that sanctification in holy living. They were “called to be his holy people, together with all those everywhere who call on the name of our Lord Jesus Christ—their Lord and ours” (cf. 1 Pet 1:14–15, recalling Lev 11:44, 45; 19:2).

The designation “holy ones” or “saints” (hagioi) is a shorthand way of referring to those who have been sanctified in Christ. “Saints” becomes Paul’s regular way of describing Christians in general (e.g., Rom 1:7; 8:27; 2 Cor 1:1; Eph 1:1), although he sometimes refers specifically to the believers in Judea in this way (e.g., Rom 15:25–26, 31; 1 Cor 16:1).¹⁴

Paul appeals again to the holy status of the Corinthians when he writes, “But you were washed, you were sanctified, you were justified in the name of the Lord Jesus Christ and in the Spirit of our God” (6:11). As in 1:30, three different expressions are used to explain how the saving work of Christ benefits us. No sequence is implied: We are not washed, then sanctified, then justified. Paul’s overall meaning is this:

Your own conversion, effected by God through the work of Christ and the Spirit, is what has removed you from being amongst the wicked, who will not inherit the kingdom. … Therefore, live out this new life in Christ and stop being like the wicked.¹⁵

The resurrected Lord Jesus is the source of new life for believers, and the reality of this is communicated to us by the Spirit, who is God’s sanctifying presence among his people (1 Cor 3:16–17; 6:19–20). Regeneration is prior to faith in Christ and makes faith possible. The benefits listed in 1:30 and 6:11 are “different facets or aspects of the one act of incorporation with the resurrected Christ.”¹⁶

Preparing for the end

God’s discipline

Hebrews 12:5–11 speaks of God’s fatherly care for his children, which includes disciplining us “for our good, in order that we may share in his holiness” (12:10). The context is opposition from opponents (12:3–4), which creates “hardship” for believers. A rare term (hagiotēs) denotes the sanctity of God’s character and life. Sharing in God’s holiness ultimately means being brought “to glory” through Christ (2:10; cf. 2 Thess 2:14). But even now, by faith, we may experience some of the blessings of the age to come in anticipation (Heb 6:4–5; 12:22–24). As we learn to submit to God’s will in suffering, something of his holy character may be seen in our lives (12:9–10). Trials of various kinds are necessary for the formation of this holy character (cf. Rom 5:3–5; Jas 1:2–4; 1 Pet 1:6–9). God “exercises” or “trains” his people in the present (Heb 12:11) to produce in them “a harvest of righteousness and peace,” the signs of a transformed and sanctified community.

The exhortation in Hebrews 12:14 to live in peace with everyone and be holy is accompanied by a warning: “without holiness no one will see the Lord.” This prepares for the challenge in 12:15–17 to care for any member of the church who may be going astray. Although a different Greek word for holiness is used (hagiasmos vs. hagiotetos), there is an echo of 12:10 here. The author highlights the wonderful prospect of seeing God, which is another way of speaking about life in his presence. The author then elaborates this motif in 12:18–24, as the basis for a final challenge not to forfeit the grace of God and the blessings of the coming kingdom (12:25–29). We are to seek holiness as a practical expression of our sanctification in Christ, remembering the promise that God is at work in our lives, so that we might finally “share his holiness.” Hebrews 13 illustrates some of the dimensions of a holy or consecrated lifestyle.

Self-control

When Paul says, “It is God’s will that you should be sanctified” (1 Thess 4:3), he has in mind a particular expression of this:

that you should avoid sexual immorality; that each of you should learn to control your own body in a way that is holy and honorable; not in passionate lust like the pagans, who do not know God; and that in this matter no one should wrong or take advantage of a brother or sister. (4:3–6)

This is a call for God’s holy people to maintain proper sexual boundaries and live differently from unbelievers. Paul reinforces his message when he says, “For God did not call us to be impure, but to live a holy life” (3:7), and adds that God gives his Holy Spirit for this very purpose.¹⁷ Self-control is a fruit of the Spirit (Gal 5:22–23), meaning that we must “walk by the Spirit” in every aspect of our lives to experience this divine enabling.

The apostle’s wish-prayer in 1 Thessalonians 5:23–24 (cf. 3:11–13) is oriented towards the return of Christ, but it also has in mind the condition of believers here and now. God is asked to sanctify his people “through and through” (NIV) or “completely” (ESV). Gordon Fee concludes that Paul wants believers

to stand blameless in holiness before God at the coming of Christ, and he insists (now in prayer) that such holiness be thoroughgoing in their lives, including the purity of the body.¹⁸

“Entire sanctification” is not a crisis moment in the process of Christian perfection, as some have proposed.¹⁹ The verb “sanctify” is used in a summary way here, as Paul asks for the complete expression in their lives of what it means to be the holy people of God, both now and on the day of judgment. A second work of grace is not implied, though sanctification clearly has a present and a future aspect (cf. Eph 5:25–27; 2 Thess 2:13–14).

Progress in sanctification

NT writers focus on the need to express our sanctification in Christ holistically, rather than suggesting that we need to become more and more holy each day. At the same time, they show how God continues to exercise or train his people, to produce in them the signs of a transformed life. Marny Köstenberger rightly affirms that the call of God to be his “holy people” (1 Cor 1:2) means to become what we already are in Christ:

As they are spiritually united to him, and in him with one another, and as the Spirit continually performs his sanctifying work in them, they grow in personal and communal holiness, being corporately set apart from the world and growing closer in their personal spiritual union with Christ in the Spirit.²⁰

The problem with designating this as “progressive sanctification” is twofold.

1. First, the progressive aspect of sanctification is often detached in common thinking from the positional aspect, although the latter is the starting point and main emphasis in biblical teaching.
2. Second, progress in holiness, godliness, and maturity can easily be viewed as an individual’s sole responsibility or goal, and failure to progress in certain ways can result in despair and a loss of confidence in God’s grace.

In my view, therefore, it is more helpful to talk about progress in sanctification, to keep the focus on the gospel framework for this challenge.

The progressive aspect of sanctification is often detached in common thinking from the positional aspect, although the latter is the starting point and main emphasis in biblical teaching.

Furthermore, although progress in sanctification must be understood in relation to other NT expectations such as renewal, transformation, growth to maturity, and glorification, it should not simply be identified with them, separately or together. Each of these biblical terms gives a different perspective on the Christian life, offering the hope of God’s enabling power and presence to fulfill his purpose for us. Moreover, sanctification in the NT is more often associated with what God has already accomplished for us in his Son and keeping us in that relationship.

Sanctification under the New Covenant is achieved by the sacrificial death of Jesus the Son of God (John 17:19; Eph 5:25–27; Heb 10:10; 13:12). The Holy Spirit, who regenerates us, enables us to trust in that finished work, applies the benefits to us personally through conversion and union with Christ (2 Thess 2:13–14; Titus 3:4–8; 1 Pet 1:2), and seals us for the final day of redemption (Eph 1:11–14). Complete sanctification of body, soul, and spirit will be accomplished by God “at the coming of our Lord Jesus Christ” (1 Thess 5:23–24; 2 Thess 2:14).

We experience sanctification when we come to believe in the gospel (John 17:17)—which is “the word of [God’s] grace” (Acts 20:32)—and we call upon the Lord Jesus for salvation (Acts 26:18), together with all those everywhere who put their trust in him and are called to be his holy people (1 Cor 1:2; 6:11).

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1. Bruce Milne, Know the Truth: A Handbook of Christian Belief (InterVarsity, 1998), 240–41. See also A. A. Hoekema, Saved by Grace (Eerdmans, 1989), 192.
2. Milne, Know the Truth, 241.
3. David G. Peterson, Possessed by God: A New Testament Theology of Sanctification and Holiness, NSBT 1 (InterVarsity, 1995), 115–37.
4. Milne, Know the Truth, 241.
5. The summary of biblical evidence that follows briefly draws on my article in T. D. Alexander and B. S. Rosner, eds., New Dictionary of Biblical Theology (InterVarsity, 2000), 544–50.
6. Jackie A. Naudé, “קָדַשׁ,” in New International Dictionary of Old Testament Theology and Exegesis, ed. W. A. Van Gemeren (Paternoster, 1997), 3:879. See the summary of Naudé’s article by Marny Köstenberger, Sanctification as Set Apart and Growing in Christ (Crossway, 2023), 8–11.
7. Köstenberger, Sanctification as Set Apart, 13–25, also relates the Bible’s teaching about the sanctification of Israel to God’s intended restoration of humanity as the image of God.
8. Köstenberger, Sanctification as Set Apart, 28–47, argues that Jesus articulates more fully what this consecrated life entails in Matthew 5–7 and John 13–17.
9. See Peterson, Possessed by God, 34–40; Gareth Lee Cockerill, The Epistle to the Hebrews (Eerdmans, 2012), 140–42, 450–53.
10. The present tense of the Greek participle translated “those who are made holy” (Heb 2:11) does not indicate a progressive sanctification in the lives of individuals, but identifies those who collectively benefit from the Son’s sanctifying work.
11. The noun hagiasmos can describe an action (ESV, “sanctification”) or the state resulting from the action (NIV, “holiness”). A double meaning may be discerned here: Christ’s sanctifying work makes it possible for us to be “set apart” or reckoned by God to be holy.
12. Roy E. Ciampa and Brian S. Rosner, The First Letter to the Corinthians (Eerdmans, 2010), 108.
13. Ciampa and Rosner, First Letter to the Corinthians, 109.
14. The move from “church” (singular) to “those sanctified” (plural) in 1 Corinthians 1:2 is significant: “Paul initially stresses the corporate solidarity of the one church in Corinth but then notes the consecrated status of each individual believer.” Ralph Cunnington, “Definitive Sanctification: A Response to John Fesko,” Evangelical Quarterly 84, no. 3 (2012): 237.
15. Gordon D. Fee, The First Epistle to the Corinthians (Eerdmans, 1987), 245.
16. Richard B. Gaffin, Resurrection and Redemption: A Study in Paul’s Soteriology, 2nd ed. (Presbyterian and Reformed Publishing Service, 1987), 131. The forensic and transforming benefits of Christ’s death are conveyed to us through union with the resurrected Lord by faith.
17. The same Greek noun (hagiasmos) is used in 4:3, 4, 7, and it could be translated “holiness” in each case, because a state or condition is implied.
18. Gordon D. Fee, God’s Empowering Presence: The Holy Spirit in the Letters of Paul (Hendrickson, 1994), 66.
19. See Peterson, Possessed by God, 51–52.
20. Köstenberger, Sanctification as Set Apart, 73.