Sanctification

involves more than a mere moral reformation of character,
brought about by the power of the truth: it is the work of the
Holy Spirit bringing the whole nature more and more under the
influences of the new gracious principles implanted in the soul
in regeneration. In other words, sanctification is the carrying
on to perfection the work begun in regeneration, and it extends
to the whole man (Rom. 6:13; 2 Cor. 4:6; Col. 3:10; 1 John 4:7;
1 Cor. 6:19). It is the special office of the Holy Spirit in the
plan of redemption to carry on this work (1 Cor. 6:11; 2 Thess.
2:13). Faith is instrumental in securing sanctification,
inasmuch as it (1) secures union to Christ (Gal. 2:20), and (2)
brings the believer into living contact with the truth, whereby
he is led to yield obedience "to the commands, trembling at the
threatenings, and embracing the promises of God for this life
and that which is to come."

Perfect sanctification is not attainable in this life (1 Kings
8:46; Prov. 20:9; Eccl. 7:20; James 3:2; 1 John 1:8). See Paul's
account of himself in Rom. 7:14-25; Phil. 3:12-14; and 1 Tim.
1:15; also the confessions of David (Ps. 19:12, 13; 51), of
Moses (90:8), of Job (42:5, 6), and of Daniel (9:3-20). "The
more holy a man is, the more humble, self-renouncing,
self-abhorring, and the more sensitive to every sin he becomes,
and the more closely he clings to Christ. The moral
imperfections which cling to him he feels to be sins, which he
laments and strives to overcome. Believers find that their life
is a constant warfare, and they need to take the kingdom of
heaven by storm, and watch while they pray. They are always
subject to the constant chastisement of their Father's loving
hand, which can only be designed to correct their imperfections
and to confirm their graces. And it has been notoriously the
fact that the best Christians have been those who have been the
least prone to claim the attainment of perfection for
themselves.", Hodge's Outlines.