The word ‘Sanctification’ (Gk. hagiasmos) is used in the Bible in various ways including, to make holy, consecration, to be separate from the world, and to be set apart for God’s purposes.
There are verses that do not use the word sanctification or sanctify, but express the standards of Christian sanctification: “Thou shalt love the Lord thy God with all thy heart, and with all thy soul, and with all thy mind” (Matthew 22:37); “To the end He may stablish your hearts unblameable in holiness before God, even our Father, at the coming of our Lord Jesus Christ with all His saints” (1 Thessalonians 3:13); “Being then made free from sin, ye became the servants of righteousness. I speak after the manner of men because of the infirmity of your flesh: for as ye have yielded your members servants to uncleanness and to iniquity unto iniquity; even so now yield your members servants to righteousness unto holiness” (Romans 6:18-19); “This I say then, Walk in the Spirit, and ye shall not fulfil the lust of the flesh” (Galatians 5:16); “Ye shall be holy: for I the LORD your God am holy” (Leviticus 19:2). These describe the work of the Holy Spirit in a believer’s life to separate him from slavery to sin and the world so that he might live a holy life unto God.
Sinless Perfection is not being described in these verses, but they do speak of personal righteousness in a fallen world. A person who has been sanctified seeks to keep his Christian character pure before God and the world, “That ye may be blameless and harmless, the sons of God, without rebuke, in the midst of a crooked and perverse nation, among whom ye shine as lights in the world” (Philippians 2:15). Paul tells us that we must walk in sanctification because God wants “to present you holy and unblameable and unreproveable in His sight” (Colossians 1:22).
A true believer has been crucified with Christ, so by God’s grace keeps free from the power and dominion of sin, “Being then made free from sin, ye became the servants of righteousness” (Romans 6:18), therefore such a person finds victory over the flesh in the Lord Jesus Christ.
The foundational truths concerning sanctification are found in the Old Testament, especially in direct relationship to the people of Israel. They were meant to be a sanctified people, that is, they were to keep themselves separate from the other nations around them, “And ye shall be unto me a kingdom of priests, and an holy nation. These are the words which thou shalt speak unto the children of Israel” (Exodus 19:6). They were to stay away from all that God said would pollute them, “For I am the LORD your God: ye shall therefore sanctify yourselves, and ye shall be holy; for I am holy: neither shall ye defile yourselves with any manner of creeping thing that creepeth upon the earth” (Leviticus 11:44). Vessels, tools, altars, and people were sanctified unto the Lord (set apart for His purposes only). In the New Testament the believer is expected to maintain holiness and sanctification, “Follow peace with all men, and holiness, without which no man shall see the Lord” (Hebrews 12:14).
Sanctification is the work of God in the lives of His people, but there must be the corresponding action (or working out of it) in our every day lives, “Wherefore, my beloved, as ye have always obeyed, not as in my presence only, but now much more in my absence, work out your own salvation with fear and trembling. For it is God which worketh in you both to will and to do of His good pleasure” (Philippians 2:12-13). In order for sanctification to be accomplished we must respond to God’s call to holiness by separating ourselves from all evil, “What shall we say then? Shall we continue in sin, that grace may abound? God forbid. How shall we, that are dead to sin, live any longer therein?” (Romans 6:1-2) even to the slightest appearance of it, “Abstain from all appearance of evil” (1 Thessalonians 5:22). The Lord does cleanse us, but in daily practice we must cleanse ourselves, “Having therefore these promises, dearly beloved, let us cleanse ourselves from all filthiness of the flesh and spirit, perfecting holiness in the fear of God” (2 Corinthians 7:1); “Let not sin therefore reign in your mortal body, that ye should obey it in the lusts thereof” (Romans 6:12); “This I say then, Walk in the Spirit, and ye shall not fulfil the lust of the flesh. For the flesh lusteth against the Spirit, and the Spirit against the flesh: and these are contrary the one to the other: so that ye cannot do the things that ye would. But if ye be led of the Spirit, ye are not under the law. Now the works of the flesh are manifest, which are these; Adultery, fornication, uncleanness, lasciviousness, idolatry, witchcraft, hatred, variance, emulations, wrath, strife, seditions, heresies, envyings, murders, drunkenness, revellings, and such like: of the which I tell you before, as I have also told you in time past, that they which do such things shall not inherit the kingdom of God. But the fruit of the Spirit is love, joy, peace, longsuffering, gentleness, goodness, faith, meekness, temperance: against such there is no law. And they that are Christ’s have crucified the flesh with the affections and lusts. If we live in the Spirit, let us also walk in the Spirit” (Galatians 5:16-25). This means then that to live a sanctified life we must keep ourselves from anything that would be offensive to God, “Pure religion and undefiled before God and the Father is this, To visit the fatherless and widows in their affliction, and to keep himself unspotted from the world” (James 1:27); “Yield your members servants to righteousness unto holiness” (Romans 6:19); “I beseech you therefore, brethren, by the mercies of God, that ye present your bodies a living sacrifice, holy, acceptable unto God, which is your reasonable service. And be not conformed to this world: but be ye transformed by the renewing of your mind, that ye may prove what is that good, and acceptable, and perfect, will of God” (Romans 12:1-2). We do this by putting Christ first in our lives and being determined to live according to His example, “But put ye on the Lord Jesus Christ, and make not provision for the flesh, to fulfil the lusts thereof” (Romans 13:14). Paul calls this going “on unto perfection” (Hebrews 6:1), since a truly sanctified Christian is not content just to have past sins forgiven, he desire to live free from sin but totally for the Lord. He sees his life as belonging to God and seeks to please God by it. It takes effort, commitment, and dedication to stay clean of the filth of this world, “Draw nigh to God, and He will draw nigh to you. Cleanse your hands, ye sinners; and purify your hearts, ye double minded” (James 4:8).
All of this could be accomplished through personal effort alone, but it still would not be Biblical Sanctification. The truly sanctified believer does not rely upon good works but stays in an intimate fellowship with the Lord Jesus Christ, “Abide in me, and I in you. As the branch cannot bear fruit of itself, except it abide in the vine; no more can ye, except ye abide in me” (John 15:4). Those living in sanctification have devoted themselves to prayer, “Continue in prayer, and watch in the same with thanksgiving” (Colossians 4:2), desire to obey God’s Word, “Sanctify them through Thy truth: Thy word is truth” (John 17:17), and are sensitive to the will and leadings of God. Those living and walking in sanctification love God’s ways but hate everything to do with evil, “Thou hast loved righteousness, and hated iniquity” (Hebrews 1:9). Even in the smallest details of their lives they desire to be obedient to the Lord.
Sanctification is not presented in Scripture as a slow work of God in our lives. Such an idea that it takes a long time is usually an excuse for personal failure and sin. The New Testament describes sanctification as a definite act of God in a life that desires to make a clean break from sin, Satan, and the world, “Being then made free from sin, ye became the servants of righteousness … If ye then be risen with Christ, seek those things which are above, where Christ sitteth on the right hand of God. Set your affection on things above, not on things on the earth. For ye are dead, and your life is hid with Christ in God” (Romans 6:18, Colossians 3:1-3). At the same time however sanctification is seen as a lifelong experience as we continue to put to death the desires of the flesh. Our Christian lives should be a progressive transformation into the likeness of Christ, “But we all, with open face beholding as in a glass the glory of the Lord, are changed into the same image from glory to glory, even as by the Spirit of the Lord” (2 Corinthians 3:18) as we grow in grace, “But grow in grace, and in the knowledge of our Lord and Saviour Jesus Christ” (2 Peter 3:18) and exercise a greater love for God and others, “Thou shalt love the Lord thy God with all thy heart, and with all thy soul, and with all thy mind. This is the first and great commandment. And the second is like unto it, Thou shalt love thy neighbour as thyself” (Matthew 22:37-39).
Sanctification can begin at the New Birth, but in practice it usually comes at some crisis point in a persons life. This is at the time we realise for the first time the desperate condition of our spiritual lives and the revelation of God’s holiness. This is the move of the Holy Spirit of God in us calling us to be separate from the world and into a closer relationship with the Lord, “And what agreement hath the temple of God with idols? for ye are the temple of the living God; as God hath said, I will dwell in them, and walk in them; and I will be their God, and they shall be my people. Wherefore come out from among them, and be ye separate, saith the Lord, and touch not the unclean thing; and I will receive you, and will be a Father unto you, and ye shall be my sons and daughters, saith the Lord Almighty” (2 Corinthians 6:16-18). As the believer is conscious of his sinfulness so he lays down his life before God, “present your bodies a living sacrifice, holy, acceptable unto God, which is your reasonable service” (Romans 12:1). In doing so he is making it clear that he desires that the Lord burn out all the filthiness of the flesh and spirit, to cleanse him from all unrighteousness, and to give him the grace to overcome the flesh and the world.
Trough sanctification is God’s work in our lives through the blood of Jesus Christ and the ministry of the Holy Spirit, our part is to put it into action. God does not sanctify us against our will. As we respond to the voice of God to separation and holiness so He sets us apart for His greater glory.