1Thessalonians 5:23(KJV): Now may the God of peace himself sanctify you completely, and may your whole spirit and soul and body be kept blameless at the coming of our Lord Jesus Christ.
Here, the Lord through Paul tells us that He wants us to experience total sanctification of our spirits, souls and bodies before the Lord Jesus returns: in this life time:
1John 4:17(KJV): By this is love perfected with us, so that we may have confidence for the day of judgment, because as he is so also are we in this world.
John 14:12(KJV): “Truly, truly, I say to you, whoever believes in me will also do the works that I do; and greater works than these will he do, because I am going to the Father.
Now what is sanctification?
It is setting something apart for only holy uses.
When we get born-again our spirits are sanctified but our souls: mind, will and emotions and our physical bodies are not yet sanctified as they still have the sin nature in them and are still used sometimes for un-holy purposes.
Galatians 5.16(KJV): So I say, live by the Spirit, and you will not gratify the desires of the sinful nature. 17For the sinful nature desires what is contrary to the Spirit, and the Spirit what is contrary to the sinful nature. They are in conflict with each other, so that you do not do what you want.
Romans 7:16-18(KJV): Now if I do what I do not want, I agree with the law, that it is good. (17) So now it is no longer I who do it, but sin that dwells within me. (18) For I know that nothing good dwells in me, that is, in my flesh. For I have the desire to do what is right, but not the ability to carry it out.
So God wants us to use the blood of Jesus, the Word of God and power of the Holy Spirit to totally clean out the sin nature from our souls and bodies, thus sanctifying them and making us totally free from sin.
Corinthians 7:1(KJV): Since we have these promises, beloved, let us cleanse ourselves from every defilement of body and spirit, bringing holiness to completion in the fear of God.
Ephesians 5:26-27(KJV): to make her holy, cleansing her by the washing with water through the word, 27and to present her to himself as a radiant church, without stain or wrinkle or any other blemish, but holy and blameless.
Hebrews 10:22(KJV): let us draw near to God with a sincere heart in full assurance of faith, having our hearts sprinkled to cleanse us from a guilty conscience and having our bodies washed with pure water.