1 Corinthians 1:30
At conversion, we are “born of the Spirit,” and from that moment the Spirit of God within us begins His sanctifying work. If we commit sin after conversion, He brings us under conviction and leads us to confess the sin and seek God’s forgiveness.
The Holy Spirit not only convicts us of sinful acts, but convicts us of the sinful nature that lies behind those acts. He also gives the saved man longings after purity and likeness to Jesus. This work of the Holy Spirit may go on for years in the heart of the believer, until at last he comes to the place of full surrender and simple faith, whereby he enters into the experience of entire sanctification, being delivered from pride, unbelief and inbred sin.
Thus we may say that at conversion there is partial sanctification, and later on a definite second experience of cleansing from inward sin and the fullness of the Spirit, which we call entire sanctification. In this experience are included the entire cleansing of the heart from all sin (1 John 1:7, 9), the entire surrender of the will to God (Romans 6:19), and the entire filling of the heart with the Holy Spirit (Ephesians 5:18).
William Booth defined holiness as the blessing of a clean heart, while John Wesley regarded it as an experience of perfect love. Spiritual power cannot exist without spiritual purity. An unclean heart brings condemnation and weakness, hindering our prayer life, robbing us of peace and weakening our witness. Purity and power must go together.
Above all, we must realize that holiness is more than a doctrine, or a theory or even an experience. It is Jesus Himself. “It is because of Him that you are in Christ Jesus, who has become for us wisdom from God—that is, our righteousness, holiness and redemption” (1 Corinthians 1:30). How true it is that Christ is our sanctification.
Allister Smith, The Ideal of Perfection