That is an excellent question. There are FOUR stages in the sanctification process, and we shall see they are set forth in chronological order. Before we list them, it is important to know that the word “sanctify” means to “set apart.”

  1. Sanctification by the HOLY SPIRIT (PRECONVERSION sanctification). We read of this in 2 Thessalonians 2:13, “But we are bound to give thanks to God always for you, brethren beloved by the Lord, because God from the beginning chose you for salvation through SANCTIFICATION BY THE SPIRIT and belief of the truth.” Here we see that before the foundation of the world God chose us in Christ to be saved (see Ephesians 1:4). At some point after we were born the Holy Spirit “set us apart to God from the world” and did His work of conviction of sin in us to show us our need of a savior. Then the gospel was presented to us, and we BELIEVED IT and were saved (Acts 16:31). So, the Holy Spirit’s work of sanctification prepared our hearts to respond to the gospel and brought us to “belief in the truth.”
  • Sanctification by the BLOOD OF CHRIST (POSITIONAL sanctification). In Hebrews 10:14 we read, “For by one offering He has perfected forever that that ARE SANCTIFIED.” After a sinner has “believed on Christ for salvation” they “are sanctified” (set apart to God) through the death and shed blood of Christ. In Hebrews 13:12 we read, “Therefore Jesus also, that He might SANCTIFY THE PEOPLE WITH HIS OWN BLOOD, suffered outside the gate.” You can read of the value and merits of Christ’s blood to do this in Hebrews 9:13-14 and 10:10. This stage of sanctification happens the moment we believed on Christ and never has to be repeated. We are seen before God “in Christ” (2 Corinthians 5:17) and this “POSITION in Christ” is ours forever!
  • Sanctification by the WORD OF GOD (PRACTICAL sanctification). Jesus said to the Father in John 17:17, “SANCTIFY them by Your truth. Your WORD is truth.” This stage of sanctification must occur every hour of every day until we get to glory. It is through the “WORD of God” that believers are “set apart to God.” The apostle Paul speaks of this in Ephesians 5:25-26, “Christ loved the church and gave Himself for her, that He might SANCTIFY and CLEANSE her with the WASHING OF WATER BY THE WORD.” We are still in a world surrounded by sin and are easily defiled and thus we need to CLEANSED from defilement by the WORD which results in us being “PRACTICALLY set apart to God.” David said in Psalm 119:9 & 11, “How can a young man cleanse his way? By taking heed according to Your WORD…Your WORD I have hidden in my heart, that I might not sin against You.”
  • Sanctification by our GLORIFICATION (COMPLETE sanctification). We see this wonderful truth in 1 Thessalonians 5:23, “Now may the God of peace Himself SANCTIFY YOU COMPLETELY; and may your whole spirit, soul, and body be preserved blameless at the coming of our Lord Jesus Christ.” This verse cannot really be fulfilled until we are taken to heaven “at the coming of our Lord Jesus Christ.” At that time, we will be perfectly sinless and will not need to be “sanctified by the Word.” How do we know this? We know this because we read in 1 John 3:2, “Beloved, now we are the children of God; and it has not yet been revealed what we shall be, but we know that WHEN HE IS REVEALED, WE SHALL BE LIKE HIM, FOR WE SHALL SEE HIM AS HE IS.” Our bodies (which still have the old sinful nature…Romans 7:14-20) will be glorified like His body (Philippians 3:20-21) thus our whole person (spirit, soul, and body) will be without sin. We will be perfectly SANCTIFIED through the endless ages of eternity!  (DO)  (681.5)