What does it mean that God is truth?

When the fulness of time came and it pleased God to give a perfect revelation of Himself in Christ, then it could be said "We beheld His glory … full of grace and truth," (John 1:14), for truth is REALITY — the revelation of all that God is, with the consequent putting of everything into its right position in regard to Him. He who knows God as revealed in Christ, and is by that knowledge taken out of the mists of error, has been brought into the realm of truth.

In Him we have the setting forth of truth itself; all truth is come to light in a world which is very much not what it appears to be. It is the most difficult thing, as you may know, to get at truth of any sort in this world. … You are living in a world, you may depend upon it, where you do not usually get what you want to get, and the more you get the faked thing, the more you realize things are not what they appear to be in this world of unreality.

He claimed to be not merely the Witness to the truth, but the very embodiment of truth itself. In the farewell discourse He had said, "I am … the truth," to His disciples; now before His adversaries the same thing is implicit in the remarkable words, "Every one that is of the truth hears My Voice." He is the truth in such absolute fashion that He is the test of every man.

He was the truth, and His speech was a true and exact presentation of Himself. This could not be said of the best and wisest of men. If we would, we cannot accurately manifest ourselves in words. If we could, we should shrink from doing it, being what we are. His words were the true revelation of Himself … What He said, that He is altogether.

The Apostles, as they looked upon Christ, saw the perfect revelation of all that God is. They saw the perfect purity of Christ, and they realised that God is light — absolute holiness. They saw the perfect love of Christ, and they realised that God is love. These are the great truths that the Apostle presses in the course of the Epistle — God is light and God is love (1 John 4:8). Life and light and love have been perfectly set forth in Christ.

In the days of the Old Testament, God dwelt in thick darkness. Certain attributes of God were revealed, but His nature had not yet been declared. The full revelation of God awaited the coming of Christ. None but a divine Person could reveal a divine Person. Thus, when Christ became flesh, we read, "The only begotten Son, which is in the bosom of the Father, He has declared Him" (John 1:18).

Throughout the scriptures there is that which God designates as 'the truth.' It is divine, and above the opinions of men, however wise and pious they may be. … 'The truth' must refer to God, who is true, but is not called 'the truth:' hence it comprises all that may be known of God, whether declared by creation or made known by revelation. Truth is not simply that which is held as dogma, but must be received in the soul. … Truth cannot be separated from the Lord Jesus, who is "the way, the truth, and the life." This is objectively; subjectively the Spirit is the truth as having come from the glorified Christ.

We know "Him that is true," for the Father has been made known in the Son. Yet the next words tell us that we are "in Him that is true, even in His Son Jesus Christ." So, "Him that is true," is an expression that covers both the Son and the Father, and we pass almost insensibly from the One to the Other. Another witness to the fact that the Son and the Father are one in Essence, though distinct in Person.

Then, having thus brought us to "His Son Jesus Christ," John says very pointedly, "This [or, He] is the true God, and eternal life." No stronger affirmation of His Deity could we have.

At last all that God is was revealed to men in a Man. He dwelt among us "full of grace and truth." The basis of all truth lies in the knowledge of God. Had that knowledge reached us apart from grace it would have overthrown us; but here was One full of both grace and truth, and dwelling among us.