Many people think sanctification is a process of getting rid of one’s sinful nature or suppressing it through determination and special devotion (keyword “sinless perfection”). Anyone who thinks this way is overlooking essential statements in the Bible:

• Lifeless things were sanctified: the Sabbath (Gen. 2:3), a mountain (Ex. 19:23), and utensils (Ex. 40:9-11).
• There is sanctification to evil (“consecrate” in Isaiah 66:17 is the same word that is otherwise translated “sanctify“).
• Christ—who never possessed a sinful nature—was sanctified by God and sanctified Himself (John 10:36; 17:19; see also 1 Peter 3:15).

Sanctification, therefore, cannot mean becoming sinless (or less sinful). Instead, it is about setting aside or “reserving” things or persons for a specific purpose. What God sanctifies for Himself must be separated from evil.

Two aspects of sanctification

God’s Word speaks of two different aspects of sanctification: a once-for-all sanctification and a practical sanctification. Peter writes to the recipients of his first letter that they had experienced the “sanctification of the Spirit” (1 Peter 1:2) but shortly afterward exhorts them to practice a holy life (1 Pet. 1:15). This distinction is crucial. Anyone who mixes the two sides comes to the wrong conclusions (especially the error that our acceptance by God is based on our sanctification efforts).

Once and for all

In everyday language, saints are often understood to be a group of people who are said to have lived for God outstandingly. God’s Word speaks quite differently. Even someone who has just been born again is already a saint. This is also the case with the Corinthians: they were “sanctified in Christ Jesus” and “called saints,” and Paul tells them: “You are sanctified” (1 Cor. 1:2; 6:11). This does not mean that they were particularly advanced in practical holiness, but that they were holy in principle—in position.

When a person is born again, he is sanctified by God: He belongs to God, and his life now has an entirely different purpose. This applies to every believer. This unique sanctification is presented in the New Testament from the following perspectives:

1. Sanctified by one sacrifice (Heb. 10:10, 14)

Here, we have the basis of our sanctification. It could only occur through the “sacrifice of the body of Jesus Christ.” Without Calvary, there can be no sanctification. The tense in Hebrews 10:10 (perfect tense) emphasizes that it is a one-time event—but with lasting effects: “By which will we are sanctified…” When it then says in verse 14, “Who are being sanctified,” this is not a contradiction. It is not about an ongoing process of being sanctified. Instead, it is an abstract expression for all who will be sanctified by God, no matter when.

Moreover, our verse explicitly says, “with a sacrifice” and “forever.” It could not be stated more clearly: It is a one-time change of position with eternal consequences.

2. Sanctification of the Spirit (1 Peter 1:2)

Here we find the active person. The verse is not entirely straightforward: “Through sanctification of the Spirit, to obedience…” We might have expected to read about obedience first and then sanctification, but it is the other way around. Why? Because it is again about sanctification that has happened once and for all. The Holy Spirit imparts a new nature to us when we are born again. This has completely different desires and abilities than our natural flesh. As a result, we are inwardly separated (sanctified) for God. The goal is the “obedience of Jesus Christ” in practical life.

3. Through faith in me (Acts 26:18)

This passage shows us how we achieve this sanctification through faith. Paul heard from Christ himself that the nations would receive an “inheritance” among those “who are sanctified by faith in me.” Sanctification is a consequence of faith, not of action.

4. Sanctified in Christ Jesus (1 Cor. 1:2)

Here we learn in whom we have this position: in Christ Jesus. How else could God regard people born as sinners (who have also sinned themselves) as saints or sanctified? Only by seeing them “in Christ” (cf. 1 Cor. 1:30).

Sanctification in practical life

So far, we have emphasized the absolute side of sanctification (our “position”). This should not give the impression that practical sanctification in our lives is unimportant. On the contrary, the more we are aware that God has reserved us for Himself once and for all, the more we will be careful to live in accordance with this in practice (i.e., consciously living as “reserved for God”).

Let us think of an heir to the throne. From birth, he is destined to rule over his country one day. He will be made aware of this fact repeatedly so that he behaves practically in accordance with his position. We find this principle again and again in the Bible: we are “children of light,” “not of the night,” and “beloved children” and should behave accordingly.

So, how does this practical sanctification take place? The following passages shed light on this.

• Through the truth (John 17:17)

The Lord Jesus asks the Father to sanctify the disciples who would be left behind in a dangerous world. So, this is about practical sanctification.

This verse shows how the process of practical sanctification takes place. The key lies in the expression “your word.” The Lord addresses the Father, so it is the Father’s word. It is about the truth but in the full light of the Father’s revelation. Anyone who reads the Bible this way will find Christ everywhere: in sacrifices, examples, the prophetic word, etc. This strengthens the affection for Him and the desire to please Him and to live for Him and with Him. In this way, one is inwardly detached from the earth and the world and thus practically sanctified.

• Through Christ in heaven (John 17:19)

The Lord says: “And for their sakes I sanctify Myself, that they also may be sanctified by the truth.” He would sanctify Himself by leaving the world, i.e., set Himself apart, and as a glorified man with the Father, would be the subject of the disciples, the object of their hearts. Only in this way can sanctification “through the truth” take place. Again, we see that it is about Christ, about occupation with and affection for Him, namely with Him as the One who accomplished the work, who went through death and to the Father. His absence on earth does not stand in the way of the disciples’ sanctification. On the contrary, it was “for them” that He would be “sanctified” or “set aside” in heaven.

• Through the washing (Eph. 5:26)

Ephesians 5 says that Christ loves the assembly. In the past, He gave Himself for them; in the future, He will present them glorified to Himself, and in the present, He practically sanctifies them. He uses the word again, but here with a slightly different emphasis: it is about its cleansing effect. It shows us things that do not correspond to God, be they thoughts, desires, or deeds. This brings us to confess and judge them before God.

• Through love (1 Thes. 3:12)

This passage shows us another interesting connection: practical sanctification is also a matter of love: “And may the Lord make you increase and abound in love to one another and to all, just as we do to you, so that He may establish your hearts blameless in holiness before our God and Father at the coming of our Lord Jesus Christ with all His saints“. The more our affections are directed towards Christ (see above) and His own, the more we are inwardly detached from the world and thus sanctified.

• Through the God of peace (1 Thes. 5:23)

God Himself brings about practical sanctification. We must be ready for it, but even then, it is His work. The Thessalonians were surrounded by many dangers, especially persecution and immorality. But Paul desired that the God of peace would keep them in practical holiness with regard to the whole person—spirit, soul, and body—and to the end of their journey.

• Cleanse yourself (2 Tim 2:21)

Here, we encounter an essential prerequisite for practical holiness: “Therefore if anyone cleanses himself from the latter, he will be a vessel for honor, sanctified and useful for the Master, prepared for every good work.” In the great house of Christianity, there are, unfortunately, people who do not behave for God’s glory. Those who live in this way become a vessel for dishonor. To be a vessel unto honor, one must not only be personally faithful but also avoid fellowship with vessels unto dishonor. This is not easy—sometimes almost a tightrope walk—but it is the only way to be “sanctified.” And the result is great: “a vessel unto honor, sanctified, useful unto the master of the house, prepared unto every good work.”

Progressive sanctification?

Some commentators speak of “progressive sanctification”; others warn against this expression. It all depends on what you mean by this expression. On the one hand, we are to grow spiritually, leading to progress in practical sanctification. But practical sanctification is not progressive in that our flesh becomes less dangerous or that we can eliminate it.

Outward sanctification

The Bible still uses sanctification in an outward sense (1 Cor. 7:14; Heb. 9:13) without consequences for eternity. For example, a person who came from Judaism but then turned away from Christ was outwardly sanctified (Heb. 10:29). Here, “sanctified” is in the aorist tense (not perfect tense), i.e., it is not assumed that this sanctification has any lasting effect (see Heb. 10:10.14 above).

Summary

Sanctification does not mean becoming sinless but being reserved for a specific purpose. Every believer is sanctified once and for all through the sacrifice of the Lord Jesus. The Spirit of God brings about this sanctification; through faith, it becomes accessible to us, and in Christ, we may be in this position. This fundamental sanctification is perfect and absolute. We cannot add anything to it, but we should live according to it. To help us in this, we have the Word of God, which purifies and occupies us with Christ, and the glorified Christ Himself as the subject of our hearts.