The subject of sanctification is one which many, I fear, dislike exceedingly. Some even turn from it with scorn and disdain. The very last thing they would like is to be a “saint,” or a “sanctified” man. Yet the subject does not deserve to be treated in this way. It is not an enemy, but a friend.
It is a subject of the utmost importance to our souls. If the Bible be true, it is certain that unless we are “sanctified,” we shall not be saved. …
Sanctification is that inward spiritual work which the Lord Jesus Christ works in a man by the Holy Ghost, when He calls him to be a true believer. He not only washes him from his sins in His own blood, but He also separates him from his natural love of sin and the world, puts a new principle in his heart, and makes him practically godly in life.
J. C. Ryle
Holiness: Its Nature, Hindrances, Difficulties and Roots (London: William Hunt and Company, 1889), 22, 23-24.