1 John 5:20

When ye read, "That we may be in His true Son Jesus Christ," think of the "true Son" of God. But this Son ye in no wise think to be the true Son of God, if ye deny Him to be begotten of the substance of the Father. For was He already Son of Man and by gift of God became Son of God, begotten indeed of God, but by grace, not by nature? Or, though not Son of Man, yet was He some sort of creature which, by God's changing it, was converted into Son of God? If you mean nothing of this sort, then was He either begotten of nothing, or of some substance. But thou hast relieved us from all fear of having to suppose that you affirm the Son of God to be of nothing, for thou hast declared that this is not your meaning. Therefore, He is of some substance. If not of the substance of the Father, then of what? Tell me. But ye cannot find any other. Consequently, the Father and the Son are of one and the same substance. This is the Homousion.

In the Scriptures both you and We read, "That we may be in His true Son Jesus Christ; He is the true God and Eternal Life." Let both parties yield to such weighty evidence. Tell us then, whether this "true Son" of God, discriminated as He is by the property of this name from those who are sons by grace, be of no substance or of some substance. Thou sayest, "I do not say that He is of no substance, lest I should say that He is of nothing." He is therefore of some substance: I ask, of what? If not of the substance of the Father, seek another. If thou findest not another, as indeed thou canst find none at all, then acknowledge it to be the Father's, and confess the Son Homousios, "of one substance with the Father."

Flesh is begotten of flesh, the Son of flesh is begotten of the substance of the flesh. Set aside corruption, reject from the eye of the mind all carnal passions, and behold "the invisible things of God understood by the means of the things that are made." Believe that the Creator who hath given flesh power to beget flesh, who hath given parents power of the substance of the flesh to generate "true sons" of flesh, much more had power to beget a "true Son" of His own substance, and to have one substance with the true Son, the spiritual incorruption remaining and carnal corruption being altogether alien therefrom.

The understanding which God gave, by which it is known that the true Son of God is coming, is the same as the mind of Christ.

Even at the end of his letter, John never stops insisting on the need for right doctrine. We have been given understanding to the extent that we have known the Son of God, who really has come into the world. This is what it means …

And we know that the Son of God has come, etc. For what could be clearer than these words? What could be sweeter? What could be said more strongly against all heresies? Christ is the true Son of God. The Father of Christ Jesus our …

This is the true God, and eternal life. He had said that the Son is the true God, and repeatedly affirms that this one is the true God. He says that this one is eternal life. Not in the way eternal life is promised to …

Having taught us which sin is unto death and which is not unto death, he then indicates who can sin unto death, and says: one adopted by God can never be afflicted by sin, whether unto death or not unto death. For having once surrendered …

And he hath given us a spiritual understanding, that we may know him, the true one -"The faithful and true witness." And we are in the true one - As branches in the vine, even in Jesus Christ, the eternal Son of God. This Jesus is the only living and true God, together with the father and the Spirit, and the original fountain of eternal life.

And we know that the Son of God is come,....

We know that the Son of God is come - In the flesh, and has made his soul an offering for sin; and hath given us an understanding - a more eminent degree of light than we ever enjoyed before; for as he lay in the bosom of the Father, he hath declared him unto us; and he hath besides given us a spiritual understanding, that we may know him who is true, even the True God, and get eternal life from him through his Son, In whom we are by faith, as the branches in the vine, deriving all our knowledge, light, life, love, and fruitfulness from him.

IT is remarkable how throughout the whole of John's Epistle he continually uses the word, "know." It has quite refreshed me to carefully read through the Epistle and to observe how, as the clock strikes the same note again and again, John seems to have kept to this monotone—"We know, we know, we know."

Plainly it is as the Mediator of ETERNAL LIFE to us that Christ is here contemplated. The Greek is, "The true God and eternal life is this" Jesus Christ, that is, In believing in Him we believe in the true God, and have eternal life.

IT is remarkable how throughout the whole of John's Epistle he continually uses the word, "know." It has quite refreshed me to carefully read through the Epistle and to observe how, as the clock strikes the same note again and again, John seems to have kept to this monotone—"We know, we know, we know." In this age, when it is fashionable not to know anything, when the professedly learned would hold us in a state of perpetual doubt and our great poet tells us that there is more faith in honest doubt than in half the creeds—and everybody seems to be bewitched with what is called "modern thought"—it is quite cheering to one's ears and delicious to one's heart to hear the bell strike out again and again, "We know, we know, we know"! After all, there is something certain somewhere, some grip for our anchor, some foundation to build our eternal hopes upon—something that can be trusted, something besides cloud and will-o'-the wisps! "We know, we know, we know." Take your pencils and read through this first Epistle of John and underline the word, "know," and you will feel the force of our remark. Look at the second Chapter—"Hereby we do know that we know Him." "He that says I know Him." "Hereby know we that we are in Him." In the 13th verse we read, "Because you have known Him." "I write unto you, little children, because you have known the Father. I have written unto you, fathers, because you have known Him that is from the beginning." "We have an unction from the Holy One and you know all things." "I have not written unto you because you know not the Truth, but because you, knowi t, and that no lie is of the Truth." And so in the third Chapter, verse after verse.

And we know that the Son of God is come - We know this by the evidence that John had referred to in this Epistle, 1Jn 1:1-4; 1Jn 5:6-8. And hath given us an understanding - Not an “understanding” considered as a faculty of the mind, for religion gives us no new faculties; but he has so instructed us that we do understand the great truths referred to. Compare the notes at Luk 24:45. All the correct knowledge which we have of God and his government, is to be traced directly or indirectly to the great Prophet whom God has sent into the world, Joh 1:4, Joh 1:18; Joh 8:12; Joh 9:5; Heb 1:1-3; Mat 11:27. That we may know him that is true - That is, the true God. See the notes at Joh 17:3. And we are in him that is true - That is, we are united to him; we belong to him; we are his friends. This idea is often expressed in the Scriptures by being “in him.” It denotes a most intimate union, as if we were one with him - or were a part of him - as the branch is in the vine, Joh 15:4, Joh 15:6. The Greek construction is the same as that applied to “the wicked one,” 1Jn 5:19, (ἐν τῷ ἀληθινᾧ en tō alēthinō.) This is the true God - o There has been much difference of opinion in regard to this important passage; whether it refers to the Lord Jesus Christ, the immediate antecedent, or to a more remote antecedent - referring to God, as such. The question is of importance in its bearing on the doctrine of the divinity of the Saviour; for if it refers to him, it furnishes an unequivocal declaration that he is divine. The question is, whether John “meant” that it should be referred to him? Without going into an extended examination of the passage, the following considerations seem to me to make it morally certain that by the phrase “this is the true God,” etc., he did refer to the Lord Jesus Christ. (1) The grammatical construction favors it. […]