We must avoid over-spiritualising what we read in the Word of God. John's new heaven and new earth for example are as truly real as the risen Lord is Himself! To spiritualise away the things of God as mere doctrine is the desperate expedient need of people who do not themselves know that reality. Further, they do not really know God at all. Many of us gather a large amount of spiritual knowledge, I fear, only to build for ourselves with it a totally false world!
Today in the Church as the body of Christ, we confuse truth and doctrine as being one, but the two are not one because they are not the same. From the heavenly or spiritual perspective, God is truth. Doctrine is what is said on earth about that truth. The Greek meaning of the word 'truth' is 'reality.' The doctrine of truth comes after that fact and not before it. The Jesus who said, "Ye shall know the truth" Himself embodies all that is the truth. Christ is Himself actually 'The Spirit of truth'!
Truth is much, much more than just a word, it is the living spirit of God Himself! The mark of our own spiritual maturity will always be that the things of God become real to us on earth because the Lord Jesus is real within us! We who are born again of the Spirit of God know the truth internally and it is from there that we have our freedom. Jesus Christ is our own personal inbuilt reality within each one of us and He alone is our truth! To know truth is to know Christ. To know Christ is to know truth and to be made free!