Calvin continues his discussion in his Brief Admonition to the Polish Brothers and draws the distinction between talking about the Persons of the Trinity in relation to each other and using the term “God” to refer to the divine essence as such.
In addition to these things, if there is anything proper to God, it is made plain by singular praises in the following words: “You at the beginning, O Yahweh, established the heaven and the earth” (Psalm 102. 26). Likewise: “Adore him, all angels” (Psalm 97.7). And yet the Apostle claims these praises for Christ (Hebrews 1.10): it therefore follows that that there the whole divine essence, which is common to Christ and the Spirit together with the Father, is designated under the name of “God.” Consequently, as often as the pretender who authored the document1 shoves his distinctions at me, I will have it at the ready to push back with the claim that where Christ is set in relation to the Father, the Persons are rightly distinguished, but where God is named simply, the Son is not excluded. And to be sure, if it is fitting for the Father alone to be “life,” the following statement of John will be false: “This is the true God and eternal life” (1 John 5.20). For I ask you, does he introduce another true God than the one who is praised in Moses and the prophets?2