When St. Athanasius debated with the Arians, his Discourses Against the Arians make it clear that the way we do theology is to see what the Christological/soteriological implications are. In the west as a whole, and Calvinism and Thomism in particular, there are numerous absurdities that arise from these presuppositional starting points, and the starting point and common ground between the two is a faulty Trinitarian view and a faulty Christology.
Here’s the proof. Calvinism says that in the garden, man was placed in a covenant of works where his nature was righteous and he could potentially “merit” his salvation for his seed. When man sinned, he became inherently corrupt, with all of the motions of his heart and actions being in some form evil. This is the language of the Westminster Confession. Evil is necessary and some aspect of man’s being. The image of God was lost to the degree that man’s heart produces only evil, we are told.
So a new man had to come and fulfill this covenant, and reverse the determinate power of evil passed on through natural conception. This man is Jesus of Nazareth, who in time and space perfectly kept all the laws of Moses, and thus “meritted perfect righteousness” from the Father as a human subject (Nestorian). Our debt and sin have provoked the hatred of God for the human race, which is our *natural state* (which God creates, and immediately hates – which is Manichaean!) and this infinite wrath is imputed to Christ, while the legal state He earned is imputed to us. There is no Calvinist theologian who has ever proposed that this imputed state – something clearly created – is a divine energy. There is no Calvinist theologian who has ever proposed that Christ’s humanity was deified by divine energy. But these doctrines are the teaching of Scripture and the 6th Ecumenical Council on the two wills of Christ.
So what we have is a Nestorian system where a human subject keeps the covenant of works and merits a created legal state. It is NOT a real theosis. It is a moral conjunction theory of both the Incarnation and our salvation – word-for-word Nestorianism, as the Letters of St. Cyril Against Nestorius make clear.
The Arians were proto-Nestorians and differed little in their theory than Nestorius. In their view, Jesus is a lesser creature who was damned by the Father at the Cross. They realized what the Calvinists don’t – that it’s senseless to say that God damns Himself. So they came up with a polytheistic view where the dude Jesus is an apotheosized man-god who underwent the rejection of God. Nestorius taught Jesus was a human person/personal subject who, through being a totally righteous dude, achieved union with the Son of God, the second Person of the Trinity. The Calvinists, when they give this some thought, usually opt for saying the humanity of Christ was damned – that human subject who meritted the righteousness and suffers under the “infinite wrath” as the Larger Catechism says. So this is just a variation on the Nestorian view. What all of these views have in common is that Jesus is not a divine Person. The Orthodox view of Scripture and the Councils is that the sole subject of all the Incarnate actions is the Logos. There’s no one else there.
If they admitted that, there is no sense at all which a human person can be there, “meritting righteousness” because “Jesus” is a divine Person and is righteousness. His humanity can only receve participation in the divine energies as communicated from the energy of His divine Person. His humanity never participates in the divine ousia, as that would be pantheism. His humanity is also never separated from or cut off from the divinity, but is deified/raised by the divine energy of the Persons. Calvinists often object to this “deification” language, but to do so would mean His humanity was not raised from the dead. Look at Mt. Tabor (the Transfiguration in Mt. 17) – what do you see? You see the diivne energy (not the essence) blasting through the veil of His humanity. Only the Eastern view makes sense of this and always has.
Jesus has to be consubstantial with us, for all aspects of our humanity to be raised/saved. If He lacks a human will, our wills are not healed. If He lacks a human soul, our souls are not healed. He must be fully human, and as many Calvinists deny, He assumed our lowly state. He assumed our nature bereft of divine life. It was precisely to communicate to that humanity His glory and eternal life that He assumed our fallen state. But Calvinists object to this because they assume human nature is now evil, if it is fallen. That is not so. Nothing God creates is evil, and clearly God still creates human nature as well as holding it in being (Col. 1). Calvinists often say that His humanity was “unfallen.” Then why did He suffer and die? This is docetism. The docetists taught that the suffering and death were phantasms and that His flesh was “heavenly” unfallen flesh. This is a gnostic view: just as gnostic as Calvinism, in that it gives evil some kind of determinate being. Nature is determined and our nature is determinately evil. Human persons are frozen in their evil nature which God creates and then hates (?) because, just like in Christ and in the Godhead, nature and Person are identified. Hebrews says He was tempted in every way as we, yet without sin. Yet, bizarrely, Calvinist think temptations themselves are sin. This text proves both that He assumed our fallen state, since temptation is a result of the fall, and that temptation itself – concupiscence – is not itself sin, as Calvin and the WCF say.
In Calvinism, then, the only reason there needs to be a representative as a man is simply because God wills it. But God’s will is not bound by anything in Calvinism/theological voluntarism. Thus, God cancelling out God’s infinite wrath is not only senseless, but makes the Incarnation needless.
Calvinism, then, is not at all predicated on an orthodox Christology, but a quasi-Nestorian approach that makes Jesus a human subject in order to salvage their Pelagian covenant of works doctrine and the imputation of sin doctrine. This is also why many of them get up in arms when they hear Theotokos, not having a clue what that means. They think referring to Mary as “Mother of God” means she caused His divinity, when what it means is that the Person she gave birth to is a divine Person. Calvinists who reject this reject it precisely on the same grounds as Nestorius. The Word became flesh. The Word – already a Person, did not assume a human Person. He did not change into man. He did not change man into the divine nature. He assumed human nature and redeemed it. That is why all human beings will be resurrected. There is no other basis for resurrection that union with Christ. But in the Calvinist scheme, Christ is not in any sense connected to the nature of the non-elect. Why, then, are the non-elect raised from the dead? Is resurrection a natural phenomena, as Pelagius taught? Of course not. Clearly, then, limited atonement falls as well.
As I mentioned, the classical scholastic version of the doctrine of the filioque is undeniable proof the West has followed Augustine’s doctrine of Absolute divine simplicity. This filioquism is predicated on the notion that the locus of action in the Godhead is not personal, but impersonal. The Spirit is said to proceed from a *relation* of two Persons (Father and Son) and is then subordinated to an impersonal operation/attribute – “love.” The “love” between the Father and Son is supposed to produce a Person, but not only is this nonsensical and subordinationist, it already presupposes what it is trying to show: the “love” (which *is* the H.S.) between Father and Son produces the H.S. Did you catch that? So the Holy Spirit produces Himself, and is simultaneously said to do so because He comes from the Father and Son. This is because a Person is identified with an energy (love). What Person does the love of the Spirit and Father produce? What Person does the love of the Spirit and the Son produce? This is ludicrous. In other words, Nature and Person are all one in God. But as St. John of Damascus and every Eastern Father have noted, “the heretics (modalists) say nature and person are the same in God.” As stated, it’s modalistic plain and no Calvinists reject the classical formulation of the filioque to my knowledge.
The filioque is, as I said, proof the West as a whole holds ADS because the entire basis for the notion is Augustinian simplicity. Augustine and the Spanish Catholics thought Arianism could be combatted through ADS and the Spirit being the glue between the Father and the Son. But it is evident why this is so bad. Western ADS then, confuses nature and Person in Godhead, makes Persons operations, and then posits an Incarnation of this divine nature. The typical western formula is like an addition problem:
Divine nature + human nature = Jesus Incarnate. But a divine nature (impersonal and shared by all) is not, strictly speaking, what became Incarnate. A single divine Person (with a divine nature) became Incarnate. The impersonal essence of God does not “act.” It does not enter into a mode of being which the other Persons do not. The Son, however, does. He became Incarnate, and not the Father and not the Spirit. The Logos, the Second Person, assumed impersonal, fallen human nature. That is the only way to cut it, and no one in the West really believes this.
In short, if Jesus is a divine Person, the entire Calvinistic scheme falls.