Chapter 13, Sections 24-29

The remainder of chapter 13 is devoted to a positive case for the Trinity, derived from Scripture. First, Calvin points out that the divine name is not confined to the Father, but is used in Scripture to describe the Son, as well. And although he does not mention him, the same can be said of the Holy Spirit from Acts 5.

He further builds his case by appealing to the unified nature of the trinity, refuting the heretics who fail to make the crucial distinction between "person" and "essence". Indeed, if we were to assert that the godhead was one in essence and three in essence, or one in person and three in person, we would rightly be accused of nonsense and irrationality. But this is not, and has never been the Christian position. Rather, we make a crucial distinction. God is one in essence, but three in person. With this understanding, all accusations of self-refutation and self-contradiction are seen to miss their mark.

As Calvin continues to lay waste to the objections of the heretics, he refutes their contention the subordination of the Son to the Father disproves the Trinity, and that the church Fathers can be appealed to in a refutation of the Trinity. As to the first, the fail to differentiate between "being" and "function". Christ does, in His incarnation, take on a subordinate role, but that says nothing about His divine nature.

When it comes to the Fathers, anyone who wishes to challenge Calvin in regard to patristics is in a battle, indeed. He was a patristic scholar of the first rank, quite familiar with Ireneaus and Tertullian, and therefore able to demolish the efforts of the heretics in their attempt to enlist these Fathers in their cause.

To conclude his discussion of the Trinity, Calvin appeals to the unity of the church. He does so, however, as a Protestant, not as a Catholic. That is, he does not appeal to the unity of the church as that which forms some kind of authoritative tradition, or to put forth some kind of majoritarian argument. After all, Calvin well remembered when Athanasius stood alone against the world in the face the Arius' denial of the deity of the Son. He does not, however, hesitate to bolster his case by setting forth the testimony of the church which ultimately and overwhelmingly, is on the side of Trinitarian orthodoxy.