“Sanctify them through Thy truth.” – John 17:17

No one can sanctify a soul but Almighty God, the great Father of spirits. He who made us must also make us holy, or we shall never attain that character. Our dear Savior calls the great God “Holy Father” in this prayer, and it is the part of the holy God to create holiness; while a holy Father can only be the Father of holy children, for like begets like.

Beloved, this sanctification is a work of God from its earliest stage. We go astray of ourselves, but we never return to the great Shepherd apart from His divine drawings. Regeneration, in which sanctification begins, is wholly the work of the Spirit of God. Our first discovery of wrong, and our first pang of penitence, are the work of divine grace. Every thought of holiness, and every desire after purity, must come from the Lord alone, for we are by nature wedded to iniquity. So also the ultimate conquest of sin in us, and the making us perfectly like to our Lord, must be entirely the work of the Lord God, who makes all things new, since we have no power to carry on so great a work of ourselves. This is a creation; can we create? This is a resurrection; can we raise the dead? Our degenerate nature can rot into a still direr putrefaction, but it can never return to purity or sweeten itself into perfection; this is of God and God alone. Sanctification is as much the work of God as the making of the heavens and the earth. Who is sufficient for these things? We go not even a step in sanctification in our own strength; whatever we think we advance of ourselves is but a fictitious progress which will lead to bitter disappointment. Real sanctification is entirely from first to last the work of the Spirit of the blessed God, whom the Father hath sent forth that He might sanctify His chosen ones. See, then, what a great thing sanctification is, and how necessary it is that our Lord should pray unto His Father, “Sanctify them through Thy truth.” ~ C.H. Spurgeon

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