I have given them Thy Word…Sanctify them through Thy truth: Thy Word is truth. – John 17:14,17

No holy life will be produced in us by the belief of falsehood. Sanctification in visible character comes out of edification in the inner faith of the heart, or otherwise it is a mere shell. Good works are the fruit of true faith, and true faith is a sincere belief of the truth. Every truth leads towards holiness; every error of doctrine, directly or indirectly, leads to sin. A twist of the understanding will inevitably bring a contortion of the life sooner or later. The straight line of truth drawn on the heart will produce a direct course of gracious walking in the life. Do not imagine that you can live on spiritual carrion and yet be in fine moral health, or that you can drink down poisonous error and yet lift up a face without spot before God. Even God Himself only sanctifies us by the truth. Only that teaching will sanctify you which is taken from God’s Word, that teaching which is not true, nor the truth of God, cannot sanctify you. Error may puff you up, it may even make you think that you are sanctified; but there is a very serious difference between boasting of sanctification and being sanctified, and a very grave difference between setting up to be superior to others and being really accepted before God. Believe me, God works sanctification in us by the truth, and by nothing else.

But what is the truth? There is the point. Is the truth that which I imagine to be revealed to me by some private communication? Am I to fancy that I enjoy some special revelation, and am I to order my life by voices, dreams, and impressions? Brethren, fall not into this common delusion. God’s Word to us is in Holy Scripture. All the truth that sanctifies men is in God’s Word. ~ C.H. Spurgeon

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