Sanctification in the Old Testament may be described primarily ritual and positional, while in the New Testament it becomes internal, moral, and Spirit-driven. That’s the core difference — and the sources confirm this.

1. What Sanctification Means in Each Testament

A. Old Testament — “Set Apart” (Formal/Ritual)

• Root idea: qadash = to set apart, consecrate, designate as belonging to God.

• Anything can be sanctified: people, objects, places, days.

• Sanctification is tied to ritual purity, the Law, and external consecration.

• OT sanctification is incomplete because the sacrificial system is incomplete (Heb 10:1). It is not valid after the sacrifice of Jesus.

  Hebrews 10: 1 "For the law [Law of Moses (OT)] having a shadow of good things to come, and not the very image of the things, can never with those sacrifices which they offered year by year continually make the comers thereunto perfect."

B. New Testament — “Made Holy” (Internal/Ethical)

• Root idea: hagiasmos / hagiazo = to make holy, morally transform.

• Sanctification becomes internal, ethical, and spiritual.

  Word: sanctified in Greek New Testament Strongs: G37 G37 source: Mickelson's Enhanced Strong's Dictionaries of the Greek and Hebrew Testaments G37 hagiazo (ha-jiy-a'-zo) v. 1. to make holy, to set apart unto God and apart (alienate) from the world. 2. (ceremonially) to cleanse. 3. (mentally) to reverence. [from G40] KJV: hallow, be holy, sanctify Root(s): G40 source: Abbott-Smith's Manual Greek Lexicon of the New Testament G37 Hellenistic form to make holy, consecrate, sanctify; [in LXX [Greek translation of OT} chiefly pi., hi.;] 1. to dedicate, separate, set apart for God; of things: Mat 23:17; Mat 23:19, 2Ti 2:21; of persons: Christ, Joh 10:36 Joh 17:19. 2. to purify, make conformable in character to such dedication: forensically, to free from guilt, 1Co 6:11, Eph 5:26, Heb 2:11 Heb 10:10; Heb 10:14; Heb 10:29 Heb 13:12; internally, by actual sanctification of life, Joh 17:17; Joh 17:19 Act 20:32 Act 26:18 Act 26:18. Rom 15:16, 1Co 1:2, 1Co 7:14, 1Th 5:23, Rev 22:11; of a non-believer influenced by marriage with a Christian, 1Co 7:14 3. In the intermediate sense of ceremonial or levitical purification: (a) of things, 2Ti 2:21; (b) of persons, Heb 9:13. 4. to treat as holy: Mat 6:9, Luk 11:2, 1Pe 3:15 (Cremer, 53, 602; MM, VGT, s.v.).

• It is grounded in Christ’s once-for-all sacrifice Heb 10: 9 Then said he, Lo, I come to do thy will, O God. He taketh away the first, that he may establish the second. The sacrifice of Christ's body once offered 10 By the which will we are sanctified through the offering of the body of Jesus Christ once for all. Note: We receive from what Jesus has done for us.

• The Holy Spirit regenerates, indwells, seals, fills, and produces fruit. E.g., 2 Thessalonians 2:13 "But we are bound to give thanks alway to God for you, brethren beloved of the Lord, because God hath from the beginning chosen you to salvation through sanctification of the Spirit and belief of the truth:" - 1 Peter 1:2 "Elect according to the foreknowledge of God the Father, through sanctification of the Spirit, unto obedience and sprinkling of the blood of Jesus Christ: "

• NT sanctification includes both positional holiness (declared holy [sanctified] after being baptized -1 Cor. 6:11) and progressive holiness (becoming holy). Ephesian 4: 13 "Till we all come in the unity of the faith, and of the knowledge of the Son of God, unto a perfect man, unto the measure of the stature of the fulness of Christ:"

2. How Sanctification Operates in Each Testament

A. Old Testament

• External consecration: washing, anointing, blood rituals.

• Law-based holiness: holiness tied to obedience to Mosaic commands.

• Objects and places sanctified: tabernacle, altar, garments, firstborn.

• People sanctified by ritual: priests, Levites, Israel as a nation.

• Moral transformation is not the primary meaning; holiness = belonging to Yahweh.

B. New Testament

• Internal transformation: heart renewal, new nature (2 Cor 5:17). 17 Therefore if any man be in Christ, he is a new creature: old things are passed away; behold, all things are become new.

• Spirit-driven holiness: fruit of the Spirit (Gal 5:22–23). 22 But the fruit of the Spirit is love, joy, peace, longsuffering, gentleness, goodness, faith, 23 Meekness, temperance: against such there is no law

• Christ-centered sanctification: believers sanctified “in Christ Jesus” (1 Cor 1:30). 30 But of him are ye in Christ Jesus, who of God is made unto us wisdom, and righteousness, and sanctification, and redemption:

• Ethical emphasis: “This is the will of God, your sanctification” (1 Thess 4:3).

• Ongoing process: “You are sanctified… now be sanctified” (Rom 6:19, 22). 22 But now being made free from sin, and become servants to God, ye have your fruit unto holiness[KJV], and the end everlasting life.

3. What Sanctification Requires in Each Testament

A. Old Testament Requirements

• Ritual purity

• Sacrifices repeated continually

• External separation from common things

• Priestly mediation

• Covenant obedience

• Holiness is symbolic and ceremonial more than moral

B. New Testament Requirements



1 Peter 1:2 (KJV) "Elect according to the foreknowledge of God the Father, through sanctification of the Spirit, unto obedience and sprinkling of the blood of Jesus Christ: Grace unto you, and peace, be multiplied."

• Faith in Christ

  1 Corinthians 1:30 (KJV) "But of him are ye in Christ Jesus, who of God is made unto us wisdom, and righteousness, and sanctification, and redemption:"
  

• Indwelling Holy Spirit

  2 Thessalonians 2:13 (KJV) "But we are bound to give thanks alway to God for you, brethren beloved of the Lord, because God hath from the beginning chosen you to salvation through sanctification of the Spirit and belief of the truth:"
  

• Moral obedience motivated by God's grace

  1 Thessalonians 4:3 (KJV) "For this is the will of God, even your sanctification, that ye should abstain from fornication:"
  

• Transformation of desires and character

  1 Thessalonians 4:4 (KJV) "That every one of you should know how to possess his vessel in sanctification and honour;"
  

• Holiness [SANCTIFICATION] is ethical, spiritual, and relational

  2 Thessalonians 2:13 (KJV) "But we are bound to give thanks alway to God for you, brethren beloved of the Lord, because God hath from the beginning chosen you to salvation through sanctification of the Spirit and belief of the truth:"

4. The Role of the Holy Spirit

A. Old Testament

• The Spirit does not indwell believers permanently.

• Sanctification is not described as Spirit-driven.

• Heart transformation is promised for the future (Ezek 36:26).

• OT sanctification is largely external.

B. New Testament

The Spirit:

• Regenerates (Titus 3:5)

  by the washing of regeneration, and renewing of the Holy Ghost

  Word: regeneration Strongs: G3824 Mickelson's Enhanced Strong's Dictionaries of the Greek and Hebrew Testaments G3824 paliggenesia (pa-liyn-ge-ne-siy'-a) n. 1. (spiritually) regeneration (the state or the act). 2. (figuratively) spiritual renovation or rebirth. 3. (specially) Messianic restoration. [from G3825 and G1078] KJV: regeneration Root(s): G3825, G1078 Compare: G342, G365, G605, G1357, G2676 Dictionary Abbott-Smith's Manual Greek Lexicon of the New Testament G3824 new birth, renewal, restoration, regeneration; (a) of persons (Plut., Phil., al.), of spiritual regeneration, (gen. attr., v. Ellic., in l), Tit 3:5; (b) of the world, as in Stoics, Jewish Apocal., al. (v. Dalman, Words, 177 ff.), Mat 19:28.†

• Indwells (Rom 8:11)

  But if the Spirit of him that raised up Jesus from the dead dwell in you, he that raised up Christ from the dead shall also quicken your mortal bodies by his Spirit that dwelleth in you.

  Word: dwelleth Strongs: G1774 G1774 Mickelson's Enhanced Strong's Dictionaries of the Greek and Hebrew Testaments G1774 enoikeo (en-oi-ke'-o) v. to inhabit (figuratively). [from G1722 and G3611] KJV: dwell in Root(s): G1722, G3611 Abbott-Smith's Manual Greek Lexicon of the New Testament G1774 [in LXX chiefly (29/36) for H3427 ] to dwell in; metaph., seq. , c. dat. pers: 2Cor 6:16; t. Rom 8:11, 2Timothy 1:14; , Col 3:16; , 2Timothy 1:5; Rom 7:17

• Seals (Eph 1:13–14)

• Fills (Eph 5:18)

• Produces fruit (Gal 5:22–23)

• Sanctification is impossible without the Spirit.

• NT sanctification is internal and external.

5. The Role of Sacrifice

A. Old Testament

• Sacrifices symbolically sanctify.

• They must be repeated.

• They cannot perfect the conscience (Heb 10:1).

• Sanctification is partial and anticipatory.

B. New Testament

• Christ’s sacrifice perfects and completes sanctification.

• “By one offering He has perfected forever those who are sanctified” (Heb. 10:14).

• Sanctification is rooted in the cross, not ritual.

• Believers are sanctified [made holy and saints) once for all (Heb 10:10; 1 Cor. 6:11).

6. Summary Table — OT vs NT Sanctification

Feature	Old Testament	New Testament
Meaning	Set apart, consecrated	Made holy, morally  transformed
Nature	External, ritual	Internal, ethical, spiritual
Agent	Priests, rituals	Holy Spirit
Basis	Mosaic Law	Christ’s sacrifice
Scope	People, objects, days, places	Believers’ hearts and lives
Process	Repeated rituals	Ongoing transformation
Goal	Ritual purity, covenant identity	Christlikeness, moral  holiness

Final Takeaway

OT sanctification is about belonging to God through ritual consecration. NT sanctification is about becoming like God through the Spirit’s inner work. But in both cases God does the sanctifying with man's positive response. For example, 1 Corinthians 6:11, "And such were some of you: but ye are washed, but ye are sanctified, but ye are justified in the name of the Lord Jesus, and by the Spirit of our God."