Put on that new man who according to God is created to righteousness and true holiness. Sanctification is not to be understood here as a separation from ordinary use or consecration to some special use, although this meaning is often present in Scripture, sometimes referring to outward and sometimes to inward or effectual separation. The term is rather to be understood as that change in a believer in which he has righteousness and indwelling holiness imparted to him. Through sanctification of the Spirit. For God himself witnesses that holiness is a gift of inherent grace.
Sanctification involves a real change of qualities and disposition.
It is called a real change so as to distinguish it not only from justification but also from sanctification by institution, which is the case in the sanctification of the seventh day. It is also distinguished from sanctification by association with symbols, such as the sanctification of the elements in the sacraments. It pertains to the whole man and not to any one part. But the whole of the man, or that whole which the man comprises, is not immediately changed. Although the whole man partakes of this grace, it is first and most appropriately in the soul and later progresses to the body, inasmuch as the body of the man is capable of the same obedience to the will of God as the soul.