In keeping with my series on the historical view of the Johannine Comma, here are the thoughts of John Calvin on the subject, even though Calvin is neither particularly favorable to the position that I favor, nor particularly dogmatic. It should be noted that apparently the Jerome document that Calvin is referencing is actually pseudo-Jerome, in light of further historical research.
The Authenticity of the Comma Johanneum
by John Calvin (1509-1564)
excerpted from his
Commentary on the Catholic Epistles
7. There are three than bear record in heaven The whole of this verse has been by some omitted. Jerome thinks that this has happened through design rather than through mistake, and that indeed only on the part of the Latins. But as even the Greek copies do not agree, I dare not assert any thing on the subject. Since, however, the passage flows better when this clause is added, and as I see that it is found in the best and most approved copies, I am inclined to receive it as the true reading.
And the meaning would be, that God, in order to confirm most abundantly our faith in Christ, testifies in three ways that we ought to acquiesce in him. For as our faith acknowledges three persons in the one divine essence, so it is called in so really ways to Christ that it may rest on him.
When he says, These three are one, he refers not to essence, but on the contrary to consent; as though he had said that the Father and his eternal Word and Spirit harmoniously testify the same thing respecting Christ. Hence some copies have εἰς ἓν, “for one.” But though you read ἓν εἰσιν, as in other copies, yet there is no doubt but that the Father, the Word and the Spirit are said to be one, in the same sense in which afterwards the blood and the water and the Spirit are said to agree in one.
But as the Spirit, who is one witness, is mentioned twice, it seems to be an unnecessary repetition. To this I reply, that since he testifies of Christ in various ways, a twofold testimony is fitly ascribed to him. For the Father, together with his eternal Wisdom and Spirit, declares Jesus to be the Christ as it were authoritatively, then, in this ease, the sole majesty of the deity is to be considered by us. But as the Spirit, dwelling in our hearts, is an earnest, a pledge, and a seal, to confirm that decree, so he thus again speaks on earth by his grace.
But inasmuch as all do not receive this reading, I will therefore so expound what follows, as though the Apostle referred to the witnesses only on the earth.