Calvin addresses the use of “extra-Biblical” theological terms in part in the Institutes of the Christian Religion 1.13. He is sympathetic of objections to words “idly devised, is superstitiously defended.” Yet his words are strong against those who object to words carefully chosen to make the doctrine more lucid. He asks, “when it has been proved that the Church was impelled, by the strongest necessity, to use the words ‘Trinity’ and ‘Person,’ will not he who still inveighs against novelty of terms be deservedly suspected of taking offence at the light of truth, and of having no other ground for his invective, than that the truth is made plain and transparent?”(3).

Such theological terms were created out of necessity, Calvin explains. “The early Christians, when harassed with the disputes which heresies produced, were forced to declare their sentiments in terms most scrupulously exact in order that no indirect subterfuges might remain to ungodly men, to whom ambiguity of expression was a kind of hiding-place”(4). Arius himself confessed that Christ was God and the Son of God, but this did not stop him from insisting that he was a creature with a beginning. The early church, Calvin says, insisted that Christ was the eternal Son and consubstantial with the Father. He continues,

The impiety was fully disclosed when the Arians began to declare their hatred and utter detestation of the term ὁμοούσιος (homoousios). Had their first confession—viz. that Christ was God, been sincere and from the heart, they would not have denied that he was consubstantial with the Father. Who dare charge those ancient writers as men of strife and contention, for having debated so warmly, and disturbed the quiet of the Church for a single word? That little word distinguished between Christians of pure faith and the blasphemous Arians (4).

We should not quickly dismiss soberly contrived theological terms. Yet Calvin is slow to “quibble” over words, noting the wide divergences between the Greek and Latin fathers on such terms. We should not “dip our pen in gall” at these men, “provided they do not in this betray pride, or petulance, or unbecoming heat, but are willing to ponder the necessity which compels us so to speak, and may thus become gradually accustomed to a useful form of expression” (5). To stop the mouth of an Arian, introduce the word consubstantial, Trinity, or essence. Calvin expresses some personal acquaintance with the importance of these words:

I was long ago made aware, and, indeed, on more than one occasion, that those who contend pertinaciously about words are tainted with some hidden poison; and, therefore, that it is more expedient to provoke them purposely, than to court their favour by speaking obscurely.