"But God be thanked, that ye were the servants of sin, but ye have obeyed from the heart that form of doctrine which was delivered you" (Romans 6:17)
I once read a book about the inner lie by a man who was not a Christian at all. He was a sharp intellectual. He examined spiritual people from the outside, but nothing ever reached him. And that is possible!
You cannot argue around this. You can read your Bible. If you are honest you will admit that it is either obedience or inward blindness. You can repeat Romans word for word and still be blind inwardly. You can quote all the Psalms and still be blind inwardly. You can know the doctrine of justification by faith, and be blind inwardly. It is not the body of truth that enlightens; it is the Spirit of truth who enlightens.
If you are willing to obey the Lord Jesus, He will illuminate your spirit. He will inwardly enlighten you. The truth you have known intellectually will now be known spiritually. Power will begin to flow up and out, and you will find yourself changed, marvelously changed.
God works for a wholly blessed end, namely, Himself: to bring the soul and her powers into that end, into Himself.
~A. W. Tozer~