A Truthscape One-Page Explainer
What Does the Bible Mean by ‘Sanctification’?
Sanctification sounds like a distant ideal. The New Testament word — the Greek hagiazo, “to set apart as holy” — is both a gift already given and a lifelong calling.
The Three Strands the Word Holds Together
Strand 1Set apart to God
Hagiazo (from hagios, holy) means to set apart, to consecrate. The root idea is belonging to God, not first moral perfection — His people are “a holy nation” (1 Peter 2:9).
Strand 2Already sanctified in Christ
A settled act at conversion: “you were washed … sanctified … justified” (1 Corinthians 6:11); believers are “sanctified … once for all” through Christ’s offering (Hebrews 10:10).
Strand 3Being made holy
And a lifelong growth: “this is the will of God, your sanctification” (1 Thessalonians 4:3); “pursue … holiness” (Hebrews 12:14). God “sanctify you completely” (1 Thessalonians 5:23).
What the Key Texts Say
| Passage | Emphasis | What it teaches |
|---|---|---|
| 1 Corinthians 6:11 | Already done | “You were washed … you were sanctified … you were justified.” |
| 1 Corinthians 1:2 | In Christ | “To those who are sanctified in Christ Jesus, called to be saints.” |
| Hebrews 10:10 | Once for all | “We have been sanctified through the offering of the body of Jesus Christ once for all.” |
| 1 Thessalonians 4:3 | God’s will | “This is the will of God, your sanctification.” |
| Hebrews 12:14 | Pursue it | “Pursue … holiness, without which no one will see the Lord.” |
| John 17:17 | By the truth | “Sanctify them by Your truth. Your word is truth.” |
| 1 Thessalonians 5:23 | God does it | “May the God of peace Himself sanctify you completely.” |
| 2 Corinthians 7:1 | Perfecting it | “Cleanse ourselves … perfecting holiness in the fear of God.” |
| 1 Peter 1:15–16 | Be holy | “Be holy in all your conduct … ‘Be holy, for I am holy.’” |
Two Common Misunderstandings
Sanctification is not first about being flawless. The root idea is being set apart to God — believers are already “sanctified in Christ” (1 Corinthians 1:2; 6:11). Holiness of life flows from belonging to Him, not the reverse.
Sanctification is neither all passive nor all effort. God sanctifies (1 Thessalonians 5:23; John 17:17), yet believers are called to pursue holiness and cleanse themselves (Hebrews 12:14; 2 Corinthians 7:1). His work and our pursuit meet.
So, What Is Sanctification?
Sanctification is being set apart to God as holy — a standing God grants in Christ and a growth He works out over a lifetime. Already His, and being made like Him: set apart once, made holy day by day. God’s work, embraced by our pursuit.
Sources & Notes Greek word study: hagiazo (Strong’s G37), “to make holy, to set apart, consecrate,” from hagios (holy). The lexicons distinguish two senses that both appear in the New Testament: to set apart or declare holy (1 Corinthians 6:11; Hebrews 10:10) and to make holy in actual life (John 17:17; 1 Thessalonians 5:23). Noun: hagiasmos (G38), “sanctification, holiness.” See Thayer’s and W. E. Vine’s dictionaries; for depth, BDAG and the TDNT (Kittel) articles. Primary texts: 1 Thessalonians 4:3–8; Hebrews 10:10–14 and 12:14. Scripture: quotations are taken from the New King James Version®. Copyright © 1982 by Thomas Nelson. Used by permission. All rights reserved. This page explains how Scripture itself uses the word, tested against the apostolic pattern; it is a definition, not a brief for any one tradition’s system of salvation.
