Sanctification is a work of the Triune God, but is ascribed more particularly to the Holy Spirit in Scripture… Though man is privileged to cooperate with the Spirit of God, he can do this only in virtue of the strength which the Spirit imparts to him from day to day. The spiritual development of man is not a human achievement but a work of divine grace. Man deserves no credit whatsoever for that which he contributes to it instrumentally.
Louis Berkhof