Matthew Poole and continuators on John 17:3

3 And this is life eternal, that they might know thee the onely true God , and Jesus Christ whom thou hast sent .

Those who deny the Divine Nature of Christ, think they have a mighty argument from this text; where Christ (as they say) speaking to his Father, calleth him the onely true God. But Divines answer, That the term onely or alone, is not to be applied to thee, but to the term God; and the sense this; To know thee, to be that God which is the onely true God; and this appeareth from 1 Iohn 5.20. where Christ is said to be the true God, which he could not be if the Father were the onely true God, considered as another from the Son. The term onely or alone, is not exclusive of the other two persons in the Trinity, but onely of Idols, the Gods of the Heathen, which are no Gods; so 1 Tim. 6.15, 16. and in many other Scriptures, so Matth. 11.27. where it is said, that none knoweth the Son, but the Father; neither knoweth any the Father, but the Son; where the negative doth not exclude the holy Spirit. Besides, the term alone, is in Scripture observed, not always to exclude all others as Mark 6.47. Our Saviour saith, it is life eternal to know him who is the onely true God; that is, it is the way to Eternal Life, which is an ordinary figure used in holy Writ.

He adds, and Iesus Christ whom thou hast sent; by which he lets us know, that the Father cannot be savingly known, but in and by the Son. Knowing in this Verse, signifieth not the meer comprehending of God, and of Christ in mens Notions, but the receiving Christ, believing in him, loving and obeying him, &c.

Marginal references: Isa. 53.11. Jer. 9.24.