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Sanctification and Assurance of Salvation in Christianity

Sanctification is the process by which believers are set apart for God's service and progressively conformed to His will [2, 7]. It is not merely a moral reformation but a work of the Holy Spirit that brings the entire human nature under the influence of new, gracious principles implanted during regeneration [1]. This process extends to the whole person [1].

The Bible describes sanctification as a separation to the service of God (Psalm 4:3; 2 Corinthians 6:17) [2]. It is effected by God the Father (Ezekiel 37:28; 1 Thessalonians 5:23), Christ (Hebrews 2:11; 13:12), and the Holy Spirit (Romans 15:16; 1 Corinthians 6:11) [2]. Believers are sanctified "in Christ" (1 Corinthians 1:2) and "through the atonement of Christ" (Hebrews 10:10; 13:12) [2, 6]. The Word of God also plays a crucial role in sanctification (John 17:17, 19; Ephesians 5:26) [2, 4]. All saints are considered to be in a state of sanctification (Acts 20:32; 26:18; 1 Corinthians 6:11) [2].

Sanctification is closely related to holiness, which in its highest sense belongs to God [7]. For Christians, holiness means being consecrated to God's service and conforming to His will (Romans 6:19, 22; Ephesians 1:4; Titus 1:8; 1 Peter 1:15) [7]. This personal holiness is a gradual development, often hindered, which necessitates watchfulness, prayer, and perseverance (1 Corinthians 1:30; 2 Corinthians 7:1; Ephesians 4:23, 24) [7]. John Gill, a Baptist commentator, describes internal sanctification as the work of the Spirit, involving a spiritual life, divine light, a will aligned with God's, and affections set on divine things, leading to an implantation of every grace in the heart. External sanctification, then, is the resulting holy life and conversation [15].

The concept of sanctification is distinct from justification, though related. Justification is a forensic, judicial act of God where He pardons sins and declares believers righteous in His sight, treating them as if they have conformed to all legal demands [5]. It is an act of a judge, not a sovereign, where the law's claims are satisfied [5]. In contrast, sanctification is the ongoing process of becoming holy, carrying to perfection the work begun in regeneration [1]. Good works are understood as the result of salvation, not its cause, flowing from a transformed heart by God's Spirit (Galatians 5:22-23) [10]. Believers are created anew in Christ Jesus for good works that God planned for them [10]. This involves stripping off the "old sinful nature" and putting on a "new nature" in Christ, allowing Him to guide their lives (Colossians 3:9-10; Ephesians 4:22-24) [12, 14].

Assurance of salvation refers to a firm conviction of one's salvation. The Greek term pistis, often rendered "faith," is used in Acts 17:31 to describe the "assurance" or pledge God gave through Jesus' resurrection that His revelation is true [3]. The "full assurance of faith" (Hebrews 10:22) implies a complete faith in God that leaves no room for doubt [3]. Similarly, the "full assurance of understanding" (Colossians 2:2) is an unwavering conviction in the truth of Scripture's declarations and a joyful steadfastness in grasping that truth [3]. This assurance is rooted in God's grace, not human actions, as salvation is through faith in God's mercy alone (Ephesians 2:8; Titus 3:5) [9]. Believers are united with Christ Jesus, sharing in His glory and blessings, and experiencing resurrection both now and in the future (Romans 6:4-14; Colossians 2:12-13; 3:1-4; Ephesians 2:6) [8, 13]. This union means they are no longer strangers but fully accepted into God's family, becoming children of God (Ephesians 2:19) [11].

Sources

  1. Easton's Bible Dictionary “Easton's Bible Dictionary: Sanctification — Involves more than a mere moral reformation of character, brought about by the power of the truth: it is the work of the Holy Spirit bringing the whole nature more and more under the influences of the new gracious principles implanted in the soul in regeneration. In other words, sanctification is the carrying on to perfection the work begun in regeneration, and it extends to the whole man (Rom. 6:13; 2 Cor. 4:6; Col. 3:10; 1 John 4:7; 1 Cor. 6:19). It is the special office of the Holy Spirit in the plan of redemption to carry on this work (1 Cor. 6:1”
  2. Torrey's Topical Textbook “Torrey's Topical Textbook: Sanctification — Is separation to the service of God -- Ps 4:3; 2Co 6:17. Effected by God. -- Eze 37:28; 1Th 5:23; Jude 1:1. Christ. -- Heb 2:11; 13:12. The Holy Spirit. -- Ro 15:16; 1Co 6:11. In Christ -- 1Co 1:2. Through the atonement of Christ -- Heb 10:10; 13:12. Through the word of God -- Joh 17:17,19; Eph 5:26. Christ made, of God, to us -- 1Co 1:30. Saints elected to salvation through -- 2Th 2:13; 1Pe 1:2. All saints are in a state of -- Ac 20:32; 26:18; 1Co 6:11. The Church made glorious by -- Eph 5:26,27. Should lead to Mortification of sin. -- 1Th 4:3,4. Ho”
  3. Easton's Bible Dictionary “Easton's Bible Dictionary: Assurance — The resurrection of Jesus (Acts 17:31) is the "assurance" (Gr. pistis, generally rendered "faith") or pledge God has given that his revelation is true and worthy of acceptance. The "full assurance [Gr. plerophoria, full bearing'] of faith" (Heb. 10:22) is a fulness of faith in God which leaves no room for doubt. The "full assurance of understanding" (Col. 2:2) is an entire unwavering conviction of the truth of the declarations of Scripture, a joyful steadfastness on the part of any one of conviction that he has grasped the very truth. The "full assurance ”
  4. I Timothy “I Timothy 4:5 (ASV) — for it is sanctified through the word of God and prayer.”
  5. Easton's Bible Dictionary “Easton's Bible Dictionary: Justification — A forensic term, opposed to condemnation. As regards its nature, it is the judicial act of God, by which he pardons all the sins of those who believe in Christ, and accounts, accepts, and treats them as righteous in the eye of the law, i.e., as conformed to all its demands. In addition to the pardon (q.v.) of sin, justification declares that all the claims of the law are satisfied in respect of the justified. It is the act of a judge and not of a sovereign. The law is not relaxed or set aside, but is declared to be fulfilled in the strictest sense; an”
  6. Hebrews “Hebrews 10:10 (ASV) — By which will we have been sanctified through the offering of the body of Jesus Christ once for all.”
  7. Easton's Bible Dictionary “Easton's Bible Dictionary: Holiness — In the highest sense belongs to God (Isa. 6:3; Rev. 15:4), and to Christians as consecrated to God's service, and in so far as they are conformed in all things to the will of God (Rom. 6:19, 22; Eph. 1:4; Titus 1:8; 1 Pet. 1:15). Personal holiness is a work of gradual development. It is carried on under many hindrances, hence the frequent admonitions to watchfulness, prayer, and perseverance (1 Cor. 1:30; 2 Cor. 7:1; Eph. 4:23, 24). (See [280]SANCTIFICATION.)”
  8. Ephesians (Protestant academic) “Tyndale House on Ephesians 2:5: 2:5 gave us life when he raised Christ from the dead (literally made us alive together with Christ): Joined with Christ, believers share in his resurrection, now and in the future (see 2:6; Rom 6:4-14; Col 3:1-4). • It is only by God’s grace that you have been saved: See Eph 1:2; 2:8-9.”
  9. Titus (Protestant academic) “Tyndale House on Titus 3:5: 3:5 not because . . . but because: The contrast is between human actions that might be thought to merit salvation and God’s grace (see Gal 2:16). Salvation is through faith in God’s mercy alone (Eph 2:8). • He washed away our sins, giving us a new birth: See Ezek 16:9; John 3:1-15; Eph 5:26; Heb 10:22; 2 Pet 1:9. • and new life through the Holy Spirit: This signifies a complete departure from the life of sin and death and a transfer into the realm of life and purity (see also Rom 12:2; 2 Cor 5:17; Col 3:10).”
  10. Ephesians (Protestant academic) “Tyndale House on Ephesians 2:10: 2:10 He has created us anew in Christ Jesus, so we can do the good things he planned for us: Good works are the result, not the cause, of salvation. God’s Spirit, working through a transformed heart, produces a good life (Gal 5:22-23).”
  11. Ephesians (Protestant academic) “Tyndale House on Ephesians 2:19: 2:19 Gentiles who believe are no longer strangers and foreigners (2:11-12, 17). Through Christ, they are fully accepted into God’s family. They become children of God, just like believing Jews (see Rom 8:14-17).”
  12. Colossians (Protestant academic) “Tyndale House on Colossians 3:9: 3:9-10 your old sinful nature . . . your new nature: Paul contrasts old and new identities (see also Rom 5:12-21; 6:6; Eph 4:22-24). Believers strip off their old life and put on Christ’s new life, allowing him to be Lord and to guide the way they live.”
  13. Ephesians (Protestant academic) “Tyndale House on Ephesians 2:6: 2:6 united with Christ Jesus: Because of this union, believers share God’s glory and blessings, and experience resurrection both now and in the future (see Rom 6:4-14; Col 2:12-13; 3:1-4).”
  14. Ephesians (Protestant academic) “Tyndale House on Ephesians 4:24: 4:24 A believer has a new nature: God’s Spirit expresses his life within the believer (see Col 3:10; cp. Gen 1:26; Rom 12:1-2; Gal 5:22-23). The transforming work of God’s Spirit is part of the gift of salvation (Eph 2:8-10).”
  15. 1 Thessalonians (Baptist/Reformed) “John Gill on 1 Thessalonians 4:3: For this is the will of God, even your sanctification,.... Which is another reason to enforce the above exhortation. "Sanctification" is internal or external. Internal sanctification is the work of the Spirit of God, and is a principle of spiritual life in the soul, a divine and spiritual light in the understanding, a flexion of the will to the will of God, and a settlement of the affections on divine things, and is an implantation of every grace in the heart. External sanctification arises from this, and lies in holiness of life and conversation; and is what ”
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