In the last few years a controversy about the Trinity has erupted in conservative evangelical circles about the relationship between God the Father and God the Son, Our Lord Jesus Christ. Some evangelicals have argued that the Son is eternally functionally subordinate to the Father, which means that the Son will always, in eternity, be subordinate or submit to the Father in all his work and roles, not merely because the Son has a human nature and subordinated himself in his incarnation, but because of eternal relationships in the Trinity. In other words, there an eternal order in the relationship between the Father and the Son, with the Son always and willingly submitting to the Father’s authority. 
Other evangelicals have insisted that who believe in the eternal functional subordination of the Son (EFS) are compromising the Son’s divinity: These evangelicals believe that EFS, by making internal distinctions between the Father and the Son, introduce distinctions into the seamless unity of the divine nature/ essence, and the one divine Will. For those opposed to EFS, those who believe in EFS are hence committing the Arian heresy; that the Son is lesser than the Father, in rank, will, and authority, and so less than fully, equally, and absolutely divine.
Now, the current debate might sound a bit like academic hair-splitting, or like those Medieval debates about how many angels could dance on the head of a pin. But, actually the debate has important practical and pastoral consequences. First, is the issue of orthodoxy and heresy. Even ordinary Christians ought to concerned with the question of the truth about God. What does the Bible say? Secondly, it concerns the worship of God: Do those who believe in EFS worship God in Spirit and in Truth? Thirdly, salvation, how exactly do we have a saving relationship with God? Is the Son’s divine nature truly and intimately involved in the Son’s obedience in history?
A Reformation Debate: Is the Son the Divine Mediator?
1. Stancaro: The Son is Not the Mediator in his Divine Nature
However, this current debate has roots in a little-known debate in church history. At the time of the Reformation, in 1560, the great Reformer in Geneva, John Calvin was dragged into a Trinitarian controversy by an Italian Protestant by the name of Francesco Stancaro.
Stancaro argued that because the divine nature is shared fully and equally between all three persons of the Trinity, Christ’s divine nature meant that he, according to his divine nature, cannot mediate or stand between God and humanity. Stancaro believed that to say that the Son mediates between the Father in his divinity as well as his humanity would imply that the Son was subordinate to the Father in his divine nature, and such an idea would be the Arian heresy; that the Son is not truly and fully God.
For Stancaro, Christ is the Mediator between God and humanity, only in his human nature, not in his divine nature. Stancaro believed that his view is in line with the ancient and orthodox doctrine of the Trinity, and the Reformers reject it at their peril. We can see the similarities here to the present debate: Some, like Stancaro, maintain that any suggestion that Christ is in any way subordinate according to his eternal divinity risks the Arian heresy.
2. Calvin: The Son is the Divine Mediator
It is here that Calvin’s response to Stancaro becomes very interesting for us. First, and crucially, for Calvin, Stancaro is guilty of allowing his theological framework to cloud the witness of Scripture. For Calvin, Scripture tells us the focus is on the Son’s relationship and dealings with the cosmos, not on God’s essence; our thoughts should be shaped by the Bible. Stancaro does not focus on the narrative of God’s dealings and does not allow Scripture to set the foundation for theological debate. For Calvin, theology must start with what the Bible says. Calvin’s discussion is shaped by what Scripture says about Christ’s cosmic mediation in Ephesians and Colossians. The doctrine of the Trinity might tell us not to talk of Christ’s mediation before Christ becomes a human, but we must follow Paul and find other ways in assert the divine equality of the Father and the Son.
Secondly, Calvin says Christ was Mediator before the incarnation: “From the beginning of creation, he already was Mediator for he always was head of the church, had primacy over the angels, and was the firstborn of every creature.” Therefore, Christ’s Mediation here must be according to his divinity, and not his human nature.
We here can bring to mind such texts as 1 Cor 8:6; Col 1:15-20, Eph 1:22f. Even more importantly, Calvin says, Christ was the “mode of communication from which otherwise hidden source, the grace of God flowed to men.” Christ is the mid-point (medium) between the Father and creation. Here, Christ’s mediation between God and creation was accomplished before the Son became human, and before the Son had a human nature. Calvin, in other words, broadens the scope of Christ’s mediatorial office of King to his person, which includes his divine nature, beyond Stancaro, who limits Christ’s mediation to his human nature. Christ as God’s vice-regent, rules the cosmos before he becomes human.
Christ’s mediation between God and creation was accomplished before the Son became human, and before the Son had a human nature. Calvin broadens the scope of Christ’s mediatorial office of King to his person
Calvin claims that the Son’s divinity did not merely enable or accompany the mediation of his human nature – Stancaro would not have denied that. Rather, for Calvin, Christ’s divinity was intimately involved in and accomplished the mediation. Therefore, the Son is the eternal and divine Mediator.
Calvin says that the Son does not fulfil all the duties of his mediatorial office merely by his atonement, as a human, rather “What does it mean… to unite us to God and to be one with God? Without doubt, these will not be found in Christ’s human nature apart from the divinity, yet they do come into consideration when it is a question of the Mediator’s office.” 
Here, the teaching of Hebrews is critical. As priest, the Son represents God to humanity and represents humanity to God (Heb 4:14; 5:5f.) Christ is our brother because he is human nature (Heb 2:12) and our guide to the Father because he is God (John 14:6.) In so far as the Son guides us to the Father – the Father has given the Son the office of being the Way. Therefore, the Son must have a different divine role or function to the Father.
Thirdly, Calvin urges that we must focus on the person of Christ; whether as a person he is the eternal Mediator. The Son, in order to mediate between God and humanity, must occupy a middle function or role between God and the cosmos. Therefore, insofar as Christ mediates in representing creatures to God the Father, he must relate to God the Father as subordinate in function.
Stephen Edmondson, the Calvin scholar, writes that “in his person as the God-human Christ is subordinate to the Father; and we should add here, given what Calvin writes of the mediation of the Word in creation and as Head of the Angels, the person of the Word, as he is active in God’s economy before and apart from the incarnation is also subordinate to the Father.”  Again, we see that Calvin’s point is confirmed by Scripture. In addition, Calvin says that in the great Christ hymn in Phil. 2 Paul places “before our eyes a complete Person composed of two natures.” For Calvin, in the narrative of John’s Gospel, which presents the Son as Mediator, the focus is not the different natures but on the person of Christ. 
What Calvin means is that our primary focus must be on the person, not the natures of Christ: Is Christ, as a person, the cosmic Mediator? The answer must be “yes.” If Christ, in his person, is the eternal Mediator, he must submit to the person of God the Father, before the fall and the incarnation.
Conclusion: Implications for Today
First, when we have theological debates, Scripture must control our thinking, not our theological framework. Ultimately, orthodoxy is the teaching of the whole Bible, not merely subscribing to a traditional understanding, however venerable and orthodox. Even the most orthodox framework can be tested and refined when we find that our systematic theology is speculative and has not adequately considered all the shape of the biblical witness. I am not calling for a narrow proof-texting approach, but a return to Calvin’s way of doing doctrine: Calvin carefully considers how the Bible’s story talks about Christ’s person and work, in dialogue with church history, and we should do the same.
In our current debate, it seems that we should search the Scriptures again. Calvin has pointed us to the important biblical concept that Christ is the cosmic Mediator in John, Ephesians, Philippians and Colossians, something that Stancaro missed in his zeal to defend Nicene orthodoxy. It may be that today critics of EFS need to consider what the Bible says: that the Son submits to the Father in more than merely his human nature. Biblically, it is quite clear: The Son as the cosmic, divine, Mediator does submit to the Father.
For Calvin, what matters is not speculative discussions about the inner life of the Trinity (what theologians call “the Trinity ad intra” or “the immanent Trinity”), but the way God the Trinity relates to the cosmos and us. Scripture tells us little about the inner life of the Trinity but stresses the way the Trinity relates to the cosmos and us in history. Our concern must be what we see about the Trinity in Scripture and how we encounter Christ as Mediator and Saviour, and not to try and pierce the mystery of the inner life of the Trinity. An important point to stress concerning Christ’s mediation is that the putative non-mediatorial life of the Son is something that we never actually encounter in revelation.
For Calvin, what matters is not speculative discussions about the inner life of the Trinity, but the way God the Trinity relates to the cosmos and us.
Second, critics of EFS should be careful about accusations of heresy. Accusations of heresy raise the stakes enormously. What is needed is to interpret brothers’ and sisters’ views with care, trust, and love. Stancaro’s attacks on the Reformers’ orthodoxy failed when Calvin showed that there can be biblical refinements and developments within the traditional doctrine of the Trinity.
Third, Calvin’s teaching about the Son being the cosmic Mediator could point the way ahead for us in our debates. All of us ought to be able to agree that the Son is subordinate to the Father in all his work as cosmic Mediator: in his vice-regency over supernatural powers, in creation, in his earthly ministry, his present ascended rule, and in his future work of judgement and new creation. Edmundson rightly comments that “the subordination, then, that Calvin describes, refers not to the ontological relationship between the Father and the Son, but rather to the loving decision shared by the Father and the Son.”
The “divine Mediation of the Son” could be a better concept than “eternal functional subordination of the Son” and may lead to an agreement between all of us.
Fourth, we must be lost in the wonder of the Son’s work of Mediation: God the Son out of love, has condescended to become the cosmic Mediator of creation and re-creation. It is only because of the Son’s work and role as Mediator can we know God and be saved. It is an extraordinary marvel surpassing human understanding, that there is both highness and lowness in God: That the God, who transcends all things, humbles himself and cares about us lowly and lost human beings, our salvation, and then exalts us with his Son.
Photo: Ivana Cajina, unsplash.com
 See the essays in eds. B. A. Ware, J. Starke, One God in Three Persons, Wheaton: Crossway, 2014.
 See K. Giles, The Rise and Fall of The Complementarian Doctrine of the Trinity, Eugene: Cascade, 2017.
 S. Edmundson, Calvin’s Christology, Cambridge: Cambridge University Press, 2004, 16-17,27.
 Edmundson, Calvin’s Christology, 31, 36-37.
 J. Tylanda, “Christ the Mediator: Calvin verses Stancaro,” Calvin Theological Journal 7 (1972):5-16, 12 cited in Edmundson, Calvin’s Christology, 28-29.
 J. Tylanda, “The Controversy on Christ the Mediator: Calvin’s Second Reply to Stancaro,” Calvin Theological Journal 8 (1972): 131-137, 147 cited in Edmundson, Calvin’s Christology, 30.
 J. Tylanda, “Christ the Mediator,” 7, cited in Edmundson, Calvin’s Christology, 30.
 Edmundson, Calvin’s Christology, 32.
 Edmundson, Calvin’s Christology,37.
 Edmundson, Calvin’s Christology, 34.
 Edmundson, Calvin’s Christology, 35.
 Edmundson, Calvin’s Christology, 38.