Sanctification explained in a single verse

"Sanctification is to be regarded as an infusion of a divine principle into the soul of a sinner, not to the exclusion of sin from his heart while he is here, not to the extermination of sin from his nature while he lives in this world, but a principle that shall affect his whole soul and his life, and this is the sanctification of the Spirit.

It is not a progressive work in the sense of making human nature better, of eradicating that principle of sin. It is not that. It is a conflict with that, it is a real conflict with that.

You have got a nature, the power of which you will experience in pulling you away and trying to separate what God has joined. Sin in the members will ever be against union, the union of Christ with His people, and will always be seeking to effect a separation between Christ and the soul, and of this separation you will have some painful feelings and experience.
A sanctified person in the gospel sense is a separated person, in whose heart dwells the life of God, that is to say, in whom is a holy principle, and that holy principle can never contentedly live away from its source and its end.

Has this blessed sanctification been wrought in you? Not in a way of progressiveness, taking some bit out of nature today and a bit more tomorrow; but subduing the whole of nature.

Sanctification is no natural goodness. Submitting your whole soul through the power of the Holy Ghost to the sovereignty of God; here is the spirit of holiness."

The above are excerpts from this article by J. K. Popham - Sanctification (truegospel.net)

 

Biblical sanctification precedes regeneration. 1 Peter 1:2, 2 Thessalonians 2:13, Hebrews 10:29.