Sanctification signifies literally a setting apart to God - like a vessel for the use of God in his temple. (See 2 Tim. 2:21.)
The ground of it is the blood of Christ. (Heb. 10:29.)
The measure of it is the person of Christ. (1 Cor. 1:30.)
The power of it is the Holy Ghost. (1 Peter 1:1, 2.)
The application of it is by the word of God. (John 17:17-19.)
Sanctification is both positional and practical.
As to position, all believers are sanctified through the offering of the body of Jesus once. (Heb. 10:10.)
To all believers, Christ is made unto them sanctification. (1 Cor. 1:30.)
All believers have sanctification of the Spirit unto obedience and sprinkling of the blood of Jesus Christ. (1 Peter 1:2.)
All believers are sanctified through the truth. (John 17:19.)
All believers are sanctified through faith. (Acts 26:18.)
As to practice, the apostle desires that the God of peace may sanctify believers wholly (oloteleis); i.e., entirely to the end. (1 Thess. 5:23.)
The will of God was their sanctification, which is divided into four parts
1st. Abstaining from fornication and uncleanness.
2nd. Positive practical holiness, which is the same word as sanctification in the original language.
3rd. Love to one another.
4th. Orderly walk, and working with their own hands. (1 Thess. 4:. 3-12.)
The Lord also prays for the believers as to practical sanctification. "Sanctify them through thy truth: thy word is truth." (John 17:17.)
The epistle to the Hebrews is the great epistle on sanctification.
The object of the apostle in writing the epistle was to separate or sanctify the Hebrew Christians from everything to Christ. They were still clinging to Judaism, the Jewish religion, which had just crucified the Lord.
Hebrews 1, 2, 3:1, 2, shows them to be sanctified brethren in association with the Son of God. Hebrews 8, 9, 10, shows them to be sanctified worshippers in association with Christ the glorified High Priest, the centre of worship.
Hebrews 12, they are disciplined to become partakers of the Father's holiness, because they were settling down in the world, and clinging to the earthly religion.
Exhortation, Hebrews 13:13.
Let us go to Him outside the camp, bearing His reproach.
If a man purge himself from these (i.e. vessels of dishonour), he shall be a vessel unto honour, sanctified and meet for the Master's use. (2 Tim. 2:21.)
My reader, the first Adam and his descendants have set themselves apart to evil and the rejection of Christ. Christ, the last Adam, set Himself apart from all evil to God, and by His death and resurrection is now fully separated to God. Do you belong to Adam, or to Christ? A. P. Cecil.