1 John 5:20

And we know that the Son of God is come, and hath given us an understanding, that we know him that is true, and we are in him that is true, even in his Son Jesus Christ. This is the true God, and eternal life.

This is the third of the three great certainties with which John concluded his epistle; and it is rather an extensive certainty. Note:

We know that the Son of God is come in the person of Jesus of Nazareth.

He hath given us an understanding (of all things that pertain to life and godliness).

We know Christ who is the true one.

We are "in Christ," having believed in him and having been baptized into the "one body," Christ's spiritual body.

This is the true God (an unqualified designation of Jesus Christ as God).

As a result of Christ's redemptive work, we enjoy eternal life (presently, in the joys of Christian service, and ultimately, throughout all eternity).

The dispute among scholars as to whether the last sentence of this verse is an affirmation of Christ's deity or not may be resolved quite easily: (1) Grammatically, there can hardly be any doubt the "true God" is a reference to Christ. (2) Theologically, it is absolutely in keeping with all that John wrote, both here and in the Gospel, to read it as a reference to Christ; and that is exactly the meaning this writer has always understood as being in the verse. Due to the extensive New Testament teaching elsewhere affirming in the most unequivocal manner the deity of the Son of God, we are compelled to agree with Plummer who wrote that, "It is of not much moment whether this particular text contains the doctrine of the Divinity of Christ or not";[30] and, of course, this is surely true in a sense. However, the very prevalence of the doctrine so frequently in view throughout the rest of the New Testament should also enter into one's willingness to see it here. It is exactly what one should have expected from the apostle John. The very discerning scholar, J. W. Roberts, pointed out the use of "eternal life" in this whole paragraph. Indeed, throughout the epistle, the fact of Jesus himself being "eternal life" is reiterated. "Jesus is eternal life."[31] With that in mind, we may view the affirmation of Christ's deity here as "the climax of John's claim for the person and work of Jesus Christ in this epistle, just as Thomas' exclamation, My Lord and my God (John 20:28) is the climax of the Gospel."[32]

[30] A. Plummer, op. cit., p. 143.

[31] J. W. Roberts, op. cit., p. 147.

[32] Ibid., p. 148.