He becomes God's property, set aside for His purposes. Contrary to the bizarre doctrines of some Pentecostal groups, a person is not sanctified before receiving the holy Ghost baptism. It is the holy Ghost which sanctifies. It is an instantaneous experience wrought by God, transferring His holiness to us by touching our souls. At the same time, there is growth in sanctification.
Entire sanctification is a process.
It is actually a growing in the knowledge of what our sanctification entails. It takes time for us to break old habits and to realize what kind of creature God has made us in Christ. Paul exhorts us to pursue this entire sanctification, to learn to live as those who have been made holy should live. And we beseech you brethren, to know them which labor among you, and are over you in the Lord, and admonish you, And to esteem them very highly in love for their work's sake. And be at peace among yourselves.