Sanctify them through Thy truth: Thy word is truth. – John 17:17

This word “sanctification” means what is commonly understood by it, namely, the making of the people of God holy. “Sanctify them,” that is, work in them a pure and holy character. “Lord, make Thy people holy,” should be our daily prayer.

O brethren, if you are called Christians, there must be no room for doubt as to the fact that you are purged from the common sins and ordinary transgressions of mankind, else are you manifestly liars unto God, and deceivers of your own souls. They that are not moral, they that are not honest, they that are not kind, they that are not truthful, are far from the kingdom. How can these be the children of God who are not even decent children of men? Thus we judge, and rightly judge, that the life of God cannot be in that man’s soul who abides wilfully in any known sin, and takes pleasure therein. We will take it for granted that you who profess to be Christians have escaped from the foul pollution of lust and falsehood; if you have not done so, humble yourselves before God, and be ashamed; for you need the very beginnings of grace. “They that are Christ’s have crucified the flesh.” But sanctification is something more than mere morality and respectability; it is not only deliverance from the common sins of men, but also from the hardness, deadness, and carnality of nature: it is deliverance from that which is of the flesh at its very best, and admittance into that which is spiritual and divine. That which is carnal cometh not into communion with the spiritual kingdom or Christ: we need that the spiritual nature should rise above that which is merely natural. This is our prayer-Lord, spiritualize us; elevate us; make us to dwell in communion with God; make us to know Him whom flesh and blood cannot reveal or discern. May the Spirit of the living God have full sovereignty over us and perfect in us the will of the Lord, for this is to be sanctified. ~ C.H. Spurgeon

https://www.blueletterbible.org/Comm/spurgeon_charles/sermons/1890.cfm