JC Ryle is one of my favorite preachers from the 19th century. In his book ‘Holiness’ he addresses the christian life in many aspects; here are chapter two’s best quotes on Sanctification:

Others are so much afraid of ‘works’ being made a part of justification that they can hardly find any place at all for ‘works’ in their religion.

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.

The faith which has not a sanctifying influence on the character is no better than the faith of devils. It is a ‘dead faith, because it is alone’. It is not the first of God. It is not the faith of God’s elect. In short, where there is no sanctification of life, there is no real faith in Christ.

Sanctification, again, is the outcome and inseparable consequence of regeneration.

Sanctification, again, is the only certain evidence of that indwelling of the Holy Spirit which is essential to salvation.

…so we may know the Spirit is in a man by the effects He produces in the man’s conduct.

Sanctification, again, is a thing which depends greatly on a diligent use of scriptural means. When I speak of ‘means’, I have in view Bible reading, private prayer, regular attendance on public worship, regular hearing of God’s Word and regular reception of the Lord’s Supper. I lay it down as a simple matter of fact, that no one who is careless about such things must ever expect to make much progress in sanctification.

A true Christian is one who has not only peace of conscience, but war within.

He that supposes works are of no importance because they cannot justify us, is a very ignorant Christian.

The notion of a purgatory after death, which shall turn sinners into saints, is a lying invention of man, and is nowhere taught in the Bible. We must be saints before we die, if we are to be saints afterwards in glory.

True sanctification does not consist in temporary religious feelings.

Many, it may be feared, appear moved and touched and roused under the preaching of the gospel while in reality their hearts are not changed at all.