Splitting the Son Destroys the Trinity

But even if this faith of the creed does not restrain your obstinacy and dishonesty, are you not, I ask you, overwhelmed by an appeal to reason and the light of truth? Tell me, I ask, whoever you are, heretic: there is, at any rate, a Trinity in which we believe and which we confess, Father and Son and Holy Spirit. About the glory of the Father and of the Spirit there is no question. It is the Son you slander, because you say that the one who was born of Mary was not the same person as the one who was begotten of God the Father. Tell me, then: if you do not deny that the only Son of God was begotten of God, who do you make out the one born of Mary to be? You say, “a mere man,” going by what he himself said: “That which is born of the flesh is flesh.” But someone who was not begotten by the law of human creation alone cannot be called a mere man. “For that which is conceived in her,” said the angel, “is of the Holy Spirit.” Even you do not dare to deny this, though you deny almost all the mysteries of salvation. [a]

He was born of the Holy Spirit, then, and cannot be called a mere man, since he was conceived by the breath of God. Now if he is not the one who, as the apostle says, “emptied himself by taking the form of a servant,” the Word who “was made flesh,” the one who “humbled himself by becoming obedient to death,” and “who for our sakes, though he was rich, became poor,” then tell me who he is, this one who was born of the Holy Spirit and conceived by the overshadowing of God? You say that he is certainly a different person. Then there are two persons: the one who was begotten of God the Father in heaven, and the other who was conceived of Mary by the breath of God. And so you bring in a fourth person. In words you call him a mere man, yet you assert that he was in fact not a mere man, since you allow (though not as you ought) that he is to be honored, worshiped, and adored.

Since, then, the Son of God who was begotten of the Father is certainly to be worshiped, and the one who was conceived of Mary by the Holy Spirit is to be worshiped, you make two persons to be honored and venerated. And you sever them from each other so far as to venerate each with an honor special and peculiar to him. So you see that by denying the Son of God, and severing him from himself, you destroy, as far as you can, the whole mystery of the divinity. For while you are trying to bring a fourth person into the Trinity, you see that you have utterly denied the whole Trinity.