Hebrews 10:10 By the which will we are sanctified through the offering of the body of Jesus Christ once for all.
Sanctification can only be attain thru the blood sacrifice of Jesus Christ and His resurrection. The question still remains as to why sanctification is necessary in the establishment of this new covenant which Christ established by His resurrection?
Allow me if you would to drag you all the way back to the beginning of all this and man’s original establishment of relationship with God.
Genesis 3:5 For God doth know that in the day ye eat thereof, then your eyes shall be opened, and ye shall be as gods, knowing good and evil.
Satan knew from experience that being in the presence of God makes you want to be like God. Adam and Eve walked with God every morning. We do not know how long they walked with God in that close personal, intimate relationship. Satan chose a time within that period that spoke something that was lingering in the heart and mind of Eve, to be like God.
In those moments before original sin, Adam and Eve had sanctification. They were separated unto God, holy, blameless and in deep personal contact with God. This is the meaning of sanctification, to be holy and separated unto God and God alone. They lost that by original sin and were cast out into the world.
Now, thru the work of the Cross of Christ, we can restore that relationship by faith. God is satisfied and relationship is restored. We are once again in the garden walking with God. Guess what? That same desire is restored in us that once hounded Eve, to be like God.
Romans 8:29 For whom he did foreknow, he also did predestinate to be conformed to the image of his Son, that he might be the firstborn among many brethren.
Now we have this promise to be conformed in the image of Jesus Christ. The method of conformation isn’t instant and we must understand that the transformation process has to begin in our minds.