The word Sanctification, agiasmoV in Greek, means to be set apart unto God. Holiness and sanctification are the same thing.

Progressive Sanctification
Paul talks about setting yourself apart. As you learn more of the word of God and begin to apply it to your life you progressively, in small steps, become more and more sanctified. (Romans 6:19)
This is done by renewing your mind with the word of God (Ephesians 5:23). Studying to show yourself approved (2 Timothy 2:15). As you study the Holy spirit will guide us into all truth (John 14:26).

Entire Sanctification
Entire Sanctification, based on 1 Thessalonians 5:23, is defined as being completely set apart to God. Not letting anything come between you and God would include sin. So to be entirely sanctified would also mean being totally sinless.
Paul even said he was mature (Philippians 3:15) but also said he had not reached perfection (Philippians 3:12). Paul even said his sin nature still manifested in him and he could not keep control of it (Romans 7:14-8:1). Paul uses the word perfection to mean maturity. (2 Corinthians 13:11)
The Holy Spirit will at times give special powers to some. For example to Samson he gave strength and to Solomon he gave wisdom. In Romans 12 and 1 Corinthians 12 we are given lists of Spiritual gifts. Prophesy, faith, ministry, teaching, exhortation, giving, leading, compassion, word of wisdom, word of knowledge, healing, discernment of spirits, tongues, interpretation of tongues. All by the Spirit’s design.

Scriptures that teach:

1. an empowerment to know God and his will for your life: (Romans 12:1-2, Ephesians 3:16-20)
2. an empowerment to stand when persecuted for your faith: (Colossians 1:11, 2 Corinthians 4:7)
3. an empowerment to make a church or mission succeed: (2 Thessalonians 1:11, 1 Corinthians 1:8)
4. an empowerment to continue defending the faith (Ephesians 6:10-11)
5. an empowerment to teach and correct: (2 Corinthians 10:4, 2 Timothy 1:7, Romans 15:13, 2 Timothy 1:14) Peter was cowardly when denying Christ three times (Luke 21:61) but bold because of the Spirit after the day of Pentecost (Acts 2).
6. separating from sinful people and situations, and purifying yourself: (2 Corinthians 7:1, Romans 13:14, Romans 6:12-13, 1 John 3:3)

Peter states God’s divine power gives us everything needed for a life of godliness (2 Peter 1:3-8). Isn’t the power to be sinless necessary to be Godly?
Why would God grant powers and gifts to men but not the power to become sinless?

In 2 Corinthians 12:9 Paul stated that the LORD would not take away his ‘thorn in the flesh’ because having that problem kept him humble. The same principle applies to us: If we become totally sinless after a short time we would become more arrogant and far less compassionate than those today, who really think they are sinless. The whole concept of Galatians 6:1-2 could never be practiced. We would not remember that it could just as easily have been us who fell into sin. Intolerance would rain supreme. If churches are fragmented now, think of what it would be like without any compassion. When you are full of pride you are out of control.

Proponents of Entire Sanctification use 2 Timothy 3:5 to state evil people will deny God’s power to make one sinless. In reality this verse states evil people deny regeneration by saying they are saved and still practicing sin.

All quotations taken from the NIV unless otherwise noted.