Sanctification is not a negative matter: βDonβt do thisβ and βDonβt do that.β It is rather the positive truth that God wants us for Himself as a sacred possession, much as a bridegroom considers his bride his very own in a special, sacred way.
Bible sanctification is a twofold truth, affecting both our standing before God and our spiritual state. In one sense every true believer in Christ has already been sanctified, or consecrated to God, by the operation of the Holy Spirit. Thus we read:
ββ¦God hath from the beginning chosen you to salvation through sanctification of the Spiritβ¦β (II Thes. 2: 13).
βElect according to the foreknowledge of God the Father, through sanctification of the Spiritβ¦β (IPet.1:2).
This has nothing to do with our conduct. God did it. Sanctification begins with Him. Thus Paul could write to even the careless Corinthian believers and say: βYe are sanctifiedβ (1 Cor. 6:11; cf. Acts 20:32; 26:18), i.e., βGod has set you apart for Himself.β This phase of sanctification is based on the redemptive work of Christ in our behalf, for Heb. 10:10 says: βWe are sanctified through the offering of the body of Jesus Christ once for all.β
But now God would have us appreciate this fact and conduct ourselves accordingly, consecrating ourselves ever more completely to Him. This is practical, progressive sanctification. βFor this is the will of God, even your sanctificationβ (I Thes. 4:3). Hence Paulβs benediction: βThe very God of peace sanctify you whollyβ (I Thes. 5:23), and his exhortation to Timothy to be βa vessel unto honor, sanctified, and meet [fit] for the Masterβs useβ (II Tim. 2:21).
How can believers be more wholly sanctified to God in their practical experience? By studying and meditating on His Word. Our Lord prayed: βSanctify them through Thy truth: Thy Word is truthβ (John 17:17), and Paul declares that βChristβ¦ loved the Church and gave Himself for it, that He might sanctify and cleanse it with the washing of water by the Wordβ (Eph. 5:25,26). source