Opera Ad Extra: The Inseparable Works of the Triune God

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Book description

The Inseparable Operations of the Trinity: An Exposition and Defense of a Dogmatic Rule

Forthcoming, Eerdmans, 2019ish.

Book Synopsis

If you have been reading up on the doctrine of the Trinity, chances are you have encountered the so-called “axiom” omnia opera Trinitatis ad extra sunt indivisa. In English, all the works of the Trinity outside of Godself are indivisible. In the literature this is sometimes referred to as the doctrine of inseparable operations (DIO). The axiom was regarded to be analytic to the doctrine of the divine unity. It is both implied by the unity of divine essence, and it implies it.

But how should the rule be understood? Is it intelligible; conceptually defensible; does it cohere with other doctrinal claims? While a variety of articles tackle various aspects of DIO, there is no book-length treatment of this important rule. Hence this project. Below is a brief synopsis and rationale for it.

I am distinguishing between (a) hard inseparability, which holds that every action token (concrete, indexed action) attributed to one of the triune persons needs to be attributed to the other two persons as well; and (b) soft inseparability, which only requires that trinitarian persons share action types (not action tokens), their concrete actions being individuated. Hard inseparability, I am suggesting, was the all but unanimous consensus of the patristic tradition. Soft inseparability is a modern innovation, most at home in social trinitarianism. I will argue against the soft version, and in favor of hard inseparability. With many significant theologians, from Athanasius, to Basil the Great, to Gregory of Nyssa, Augustine, Maximus, and Hilary of Poitiers, I will argue that we must resist views of trinitarian agency which imagine the three cooperating through their individual actions. Rather, the triune persons act as a single agent in creation, redemption, glorification, yet every such inseparable operation exhibits a threefold modality: from the Father, through the Son, in the Holy Spirit. Such a modality coheres with the manner in which the divine persons share in the divine substance.

The hard version of DIO is not without its challenges. The first obstacle is the apparent differentiation between the actions of the triune persons, as they are narrated in Scripture. It will be shown, however, that Scripture is rather clear not only about the distinction between the persons, but on the inseparability of their actions. A second challenge is of the dogmatic order: if every action token must be assigned to each person, should one not assign the incarnation to the Father and the Holy Spirit also, with the absurd result that the Father too was incarnate? Or the crucifixion, with the problematic implication that the Father died on the cross? What about the cry of dereliction? Doesn’t Scripture require us to admit a separation between the Father and the Son, at least on the cross? A further differentiation between the respective agencies of the Son and Spirit is apparent in the ascension/Pentecost “exchange:” the Son must ascend, before the Spirit can come. Finally, how are we to understand the indwelling of the Holy Spirit from the perspective of DIO?

It is quite clear that a thorough defense of DIO requires addressing each of these tough questions. But the project is one that leads to deeper contemplation of God. It eventually will yield an account of trinitarian agency that is heavily informed by a doctrine of the missions of the Son and Spirit, which preserves divine transcendence, yet affirm his intimacy to creation. It will further need to incorporate a biblical hermeneutics of trinitarian agency; an account of divine action that is informed by both contemporary philosophy of action, as well as trinitarian metaphysics. A provisional outline of the book’s chapters will follow in a separate post.

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Recovering the Doctrine of Divine Missions for Evangelical Theology

One of the biggest surprises of my research into the doctrine of inseparable operations (DIO) was the discovery of the doctrine of divine missions (DDM). Augustine is the first theologian (I may be wrong here) that unpacks the metaphysics of DDM. After him, DDM becomes replete in the West. It still remains an important locus of Catholic theology.

What makes DDM special? While other traditions also talk about the missions of the Son and the Holy Spirit, in the West DDM has become almost an integrating motif. It is carefully correlated with a theistic metaphysics. That means that it interprets the scriptural language of the sending of the Son and the Holy Spirit by bringing to bear the theology of divine attributes (simplicity, immutability, omnipresence, divine unity, etc.). DDM has thus come to dogmatically anchor reflection on Christology, pneumatology, soteriology, ecclesiology, eschatology.

The following are the essential elements of DDM:

a. A divine person that is sent never leaves! The Son and the Spirit never stop proceeding from the Father, in the unity of the divine essence, when they come to live with us and in us. Nothing is more important for soteriology than this claim that God is the reconciler, not someone else. In a person that is sent the whole Trinity resides, since the relation of procession is not broken. Here’s a quick consequence of this: it is absurd to speak of a rift (abandonment, etc.) between Father and Son in the work of redemption.

b. A divine person that is sent never arrives in a place he didn’t already inhabit. We must resist thinking of the divine persons as climbing up and down the ‘ontological ladder’. That’s an Olympian view of God. A divine mission is not simply a divine person’s coming to be with us, but rather our being drawn to union with the divine persons. The Son came into the world, but he was already in it (and the world did not know him!); the Holy Spirit was sent into the world which he is already animating and whose life he is already sustaining.

But why would this have been surprising? For the simple reason that in Protestant, and consequently in Evangelical theology, DDM faded from our collective memory. Let me explain that: it’s not as if our theologians are ignorant of the missions of the two divine persons. Rather, DDM is no longer (a) the integrative motif it once was; (b) articulated with close attention to the metaphysics of divine attributes. Not even in Protestant scholasticism does DDM make a comeback. (I have yet to look at Protestant Thomists like Zanchi and Vermigli, but I ain’t holding my breath).

One may speculate about the reasons why the DDM slipped into oblivion in Protestant circles. My best guess is that it has to do with the anti-metaphysical penchant of some early Protestant theology. But there are other possibilities.

In my own work, DDM became the key that unlocks what I think is a more biblical understanding of divine action. I will briefly sketch out some reasons why I think DDM should be recovered:

  1. DDM is the fundamental locus for thinking through the diversity and distinction between the divine persons. The diversity of the triune persons is manifested not in the production of creatures (exitus), but in the return of creatures (reditus) to God. This is the key to understanding the truth of DIO and the diversity of the persons.
  2. It properly anchors soteriology, this all important Evangelical locus, in the being and action of God. Some evangelicals are already doing some fantastic work here. I’ll single out Adam Johnson’s work, with much inspiration from Barth (and others).
  3. It provides the dogmatically proper framework for reflection on the sacraments, in particular the Eucharist. DDM is about the salvific presence of the trinitarian persons; the Eucharist is about the continued presence of the Son.
  4. It helps move theology beyond the dichotomy between the immanent and economic trinity. The work of Bruce Marshall of SMU is of signal importance here. The distortions to which this conceptuality of immanent/economic has led to are legion.
  5. Evangelical theology needs more metaphysics, not less. DDM, with its metaphysically careful distinctions, provides a much needed corrective to common interpretations of divine action in history.
  6. We need DDM to critically dialogue with with the energetic missiological work on Missio Dei. With its emphasis on the inseparability of the missions of the Son and the Spirit, DDM can provide much needed balance for missiology in a pluralistic context.


Some Evangelical theologians are already beginning to recover DDM. Here are just some of the authors I came across, roughly in the order in which I encountered them.

  1. Keith Johnson’s Rethinking the Trinity and Religious Pluralism: An Augustinian Assessment. Keith stays fairly close to Augustine’s work on the divine missions, but the critical engagement with the likes of Dupuis, D’Costa and others is illuminating.
  2. Chris R J Holmes’ The Holy Spirit, of Zondervan’s New Studies in Dogmatics series, is also exciting. He explicitly approaches the doctrine of the Holy Spirit through DDM.
  3. Fred Sanders’ The Triune God, of the same Zondervan series, has chapters on the divine missions. His approach is largely, though not exclusively, focused on the knowledge of the Trinity, and revelation. DDM works charms here since the mission of the Son is precisely to make the Father known!
  4. These are the ones that come to mind; there might be others and I’d be grateful if you would point them out to me.

Ascension and Pentecost

Why must the Son ascend before the Spirit may come? This question poses a special problem for the doctrine of inseparable operations (DIO). If the triune persons always act together, what explains the appearance of a substitution? It appears as if one divine player must leave the field/court to allow a substitute to come in. What’s going on here? Couldn’t Christ have sent the Spirit before his departure?

I’d like to suggest that a solution to this problem must be sought through the framework of the doctrine of the divine missions. Indeed, this apparent substitution bears directly on the doctrine of the missions, since it appears as if the mission of the Son ends with the ascension, while the Spirit’s mission commences at Pentecost.

I will only briefly indicate where I will be probing for an answer, leaving a fuller account for publication.

Taking Augustine and Aquinas as our guides, a mission of a divine person may be understood as the extension of a procession to include a created effect. And now in English: the coming forth of the Son/Spirit from the Father (procession) is extended towards the creature. The Son and the Spirit, who come out of the Father, pour out, so to speak, from the tranquil Trinity into the world. This may be expressed differently: bits of the world are drawn into the relations which exist within the life of the Trinity. The mission of the Trinity is to draw the world and to make it participate in the triune life (in various ways).

How does this understanding of the missions help us with our question? One implication of the doctrine of the divine missions is that a mission is the expression and extension of a procession. Thus, Jesus of Nazareth is the human expression of the Son’s eternal procession. Put differently, the created human nature of Jesus Christ has been hypostatically united to the eternal Son. The eternal procession of the Son is now expanded to include Christ’s human nature; the eternal Speaking by the Father of the Divine Logos now has an economic, created echo.

We’re close to an answer now; bear with me. The question seeks to correlate Ascension with Pentecost.

If the Son’s mission is an echo of his eternal procession, the Spirit’s mission will likewise be an echo of his own eternal procession.

But the Spirit’s procession is from the Son and the Father (according to Western Filioque). The Spirit proceeds from the love which the Son returns to the Father. The Spirit is the common gift between the Father and Son, a gift which in a certain way originates with the Father.

We are now in a position to give our answer. Just as in the immanent Trinity, the Spirit proceeds from the Son’s reciprocating the Father’s love, so economically, the mission of the Spirit presupposes the Son’s return to the Father in full submission (as human). Only this time, the Son’s returning the love of the Father happens in and through the Son’s created humanity. This is the obedience, love, and sacrifice of the second Adam.

For that reason, the mission of the Spirit is the completion of the overflow of Trinitarian life into creation. The mission of the Spirit is mediated through the humanity of Jesus Christ, which reciprocates in full obedience the love of the Father, being filled to overflow with the Spirit. For that reason Christ, the second Adam, became a life-giving Spirit (1 Cor 15:45).

There is no real substitution here. Christ has never left. He remains true to his promise to be ‘with us forever’. The humanity which the eternal Son in-dwelt, being fully submitted and sacrificed to God, now became itself a spring of living water (Jn 19:34). Christ in his very humanity became a re-spirator of the Spirit.

[Note: A fuller version of this argument will be published at some point in the near future. This is only a sketch of an argument.]

Where may the Trinity be found?

I continue to blog through the writing process of a book on the inseparable operations of the Trinity. This short post will enunciate a simple thesis, which flows from the basic premise, opera ad extra indivisa sunt. I have first presented this thesis at the Dabar 2017 conference (@ TEDS). It may be formulated as follows:

The diversity of Trinitarian persons is manifested in their self-differentiation not so much in creation’s exitus (or production), as in its reditus (or return).

The thesis derives naturally from the doctrine of inseparable operations (DIO). If God acts as a single efficient cause, it follows that the persons may not be manifested in their self-differentiation in the production of creatures, or in the divine action.

The vestiges of the Trinity, identified by Christian theologians throughout the centuries must not be confused with particular effects of the particular divine persons (such as the Father might be producing this, the Son or Spirit, that other thing). Vestiges are understood as vestiges only once the individuation of the divine persons has been made.

But, crucially, the individuation of a divine person (in distinction from the others) is not accomplished from their efficient causality (which is single).

This is the reason why the persons of the Trinity may only be identified from their union with creatures. Or, to use Augustine’s and Aquinas’s terminology, from their missions (which consist of the processions, to which a created effect is added).

This is my explanation why Scriptural revelation starts with divine monotheism and only subsequently discloses the diversity of the three persons. We start with the one God because creation is produced by the single divine efficient cause. However, creation was meant for union with God, in the person of his Son. Only insofar as creation is united to the Son, or another divine person, will the Son be individuated as distinct from the Father, and the Holy Spirit. DIO does not encourage us to expect separate actions of separate agents from above. That sounds like an Olympian view of the Gods. The Christian God is the One Holy God, who acts mightily as one in the world he has created.

But then how did we come to individuate the Son and the Holy Spirit as distinct from the Father – if they always act as one, that is? The answer is: from the fact that by faith we confess certain created realities to be united, or to manifest specifically one of these persons (even if these created realities are produced by the whole Trinity). Take Jesus Christ: in Christ, a created reality (Jesus’ human nature) is united to (and ‘actuated’ by) the eternal Son of God. This is the hypostatic union. The New Testament writers confess this to be the first fruits of the renewed creation. Or, to change examples: take the dove that descended at Jesus’ baptism: it manifests the Spirit exclusively, not because it is hypostatically united to the Spirit, but because it has been designated for that purpose. There is only a semiotic union here, not a hypostatic union.

Augustine explains the logic of these distinctions in his interpretation of Jesus’ baptism in Sermon 52. He writes that the human nature of Jesus and the dove were created by the whole Trinity (exitus); nonetheless, they specifically manifest, or are united with (in the case of Jesus) with just one of the persons (reditus).

And thus the revelation of the Holy Trinity takes place not through mere divine action, but through Trinitarian union with the creatures, hence through creation’s return to God.

Let me try an analogy here: take the operation of a magnet upon a metallic pin. The whole magnet attracts the pin, or it acts as a single efficient cause upon the pin. Nonetheless, the pin becomes attached to just one of the poles of the magnet. In being attached to one of the poles, it receives the charge of the opposite pole (I am tempted to make something trinitarian of this aspect of the example, but I must resist at this time). Similarly, the human nature of Jesus is attracted into union with God by the whole Trinity, yet it becomes attached to the Son alone. Just like we come to learn of the distinction between North and South in magnets precisely because of how metallic objects are attached to particular poles, so we come to learn the distinction between the triune persons by watching the assumption of the human nature of Jesus into union with the Son; and the manifestation of the Holy Spirit by the dove, or by tongues of fire, etc.

Preaching the Trinity: Reflections on Trinity Sunday 2017

Dorothy Sayers once wrote that the Christian ‘dogma is the drama’. Churches and preachers are called to revisit this drama every Sunday. Christian dogma is sufficiently dramatic to capture the imaginations and emotions of worshippers. But how does one preach the central Christian dogma, the doctrine of the Trinity? The dramatic effect of this dogma is often congested behind the stuffiness of technical formulations: nature, persons, subsistent relations, perichoresis, processions, etc. Below are a few tips:

  1. Always start with Scripture. The dogma of the Trinity is not an extraneous imposition upon the narratives, but the collective judgment of the church that it captures their full meaning. Whether one looks at the gospel stories, at the epistles, or at Revelation, one misreads the story of Jesus without the central truth that in him the fullness of God has been revealed. Christ is Emmanuel, God with us!
  2. Do not be afraid to use limited analogies: the three leafed clover, the divine family, even the egg analogy (shell, yolk, white). Tradition supplies a number of these analogies, neither of which is perfect: Tertullian’s root/stem/fruit, Augustine’s being/knowledge/love, Barth’s revelation/revealer/revealedness. Pop culture also supplies us with some interesting analogies: Michael Jordan’s Gatorade commercial ’23 vs 39′ (I am indebted to Adam Johnson of Biola for pointing me to this). Even the fidget spinner may be a useful prop in some settings. Since no single analogy is perfect (in fact, each taken by itself can lead to serious distortions), it is best to use several at one time. Remember that the role of the analogy is not to explain but to evoke, or to intimate. That is, while God may not be known perfectly, we are called to witness to his glorious reality through the best means we have.
  3. Show the practical value of the doctrine. Scripture consistently (and naturally) connects the Trinity with worship. Baptism is done in the name of the Triune God; prayers are meant to give glory to the Father, through the Son, in the Holy Spirit. In prayer we are not left to our own devices, but the Spirit intercedes for us, prays with us and in us (Rom 8); Our justification and salvation consists in our being engrafted into Christ, made children of God by adoption, through him who is the natural Son of God. As my good colleague, Donald Fairbairn likes to put it: to be saved is to be brought into the Father-Son relationship. Our sanctification too is such that we are made ‘partakers of the divine nature’ (2 Pet 1:4).


Go, and preach the Triune God boldly!

Book Outline: The Inseparable Operations of the Trinity

Below is a provisional outline of the book. Square brackets indicate the nature of the chapter. Exposition chapters are largely descriptive of the doctrine of inseparable operations (DIO). Analytical chapters assess the conceptual intelligibility and coherence of various components of DIO. Finally, constructive chapters lay out its dogmatic implications from creation to beatific vision.



  1. [Exposition] Triune Action in Scripture
  2. [Exposition] Inseparable Operations in Historical Perspective
    1. Patristic (Athanasius, Cyril of Alexandria, Basil the Great, Gregory of Nyssa, Augustine)
    2. Medieval (Aquinas, Duns Scotus)
    3. Eastern Trajectories: Divine Energies  (Cappadocians, Maximus, Palamas, Lossky, Staniloae etc)
    4. Post-Reformation (John Owen)
    5. Modern: Critique and Reinterpretation (Rahner, LaCugna, Pannenberg, social trinitarianism); Defense (Barth, Lonergan)
  3. [Exposition] The Divine Missions
  4. [Analytical] Individuation and Appropriation
  5. [Analytical] Soft Inseparability and Social Trinity
  6. [Analytical] The Causality of the Trinitarian Persons: Modes of Action
  7. [Analytical] The Incarnation of the Son Alone
  8. [Constructive] Creation and Trinitarian Description
  9. [Constructive] Spirit Christology and the Actions of the Incarnate Son
  10. [Constructive] The Crucifixion and the Relations between Father and Son
  11. [Constructive] Ascension, Pentecost, and Divine Presence/Agency in the Church
  12. [Constructive] The Indwelling Spirit and the Beatific Vision

Why the Doctrine of Inseparable Operations Matters

Attention to the doctrine of inseparable operations (DIO) of the Trinity protects us from being either functional unitarians, or functional tritheists. Functional unitarians disregard the real distinctions between the divine persons; functional tritheists divide the divine nature. True Biblical trinitarianism is not affirmed solely by attention to DIO, but the latter forces us to properly interpret the ‘economic’ actions of the divine persons. What does this look like in practice?

  1. Creation. While Irenaeus’ metaphor of the Son and Spirit as the hands of God is helpful, we must resist thinking of them as ‘instrumental agents’ of the Father’s work. Neither, however, is the Son simply the (Platonic) ‘mind’ of an undifferentiated God. The differentiation of the persons must be preserved as much as the unity of substance. But how?
  2. Incarnation. The Son comes, but not such that the Father is only extrinsically ‘represented’ by the Son. The mutual indwelling of the Father, and Son, and Spirit is precisely what makes the incarnation salvific. Christ is not yet another intermediary, but the fullness of the divine Trinity. Yet only the Son has become incarnate, not the Father, or the Spirit.
  3. Actions of the Incarnate Son. How does the inseparable agency of the trinitarian persons deploy through the hypostatic union? This is a perplexing question. On the one hand we want to affirm that God is acting in Christ; on the other hand, we want to retain Christ’s representativeness for us (that we may identify with him and follow him). The dilemma is as follows: on the one hand, unless Jesus is God acting for the reconciliation of the world, he may not be regarded as our Savior. On the other hand, unless Jesus is a real human being with whose actions we may identify (resisting temptation, miracles?), he is of no priestly use to us.
  4. Cross. Does the Father abandon the Son at the cross? DIO suggests that any such abandonment is unthinkable, when the Son is regarded in terms of his divine nature. The Father-Son relation is constitutive of their eternal identities. Break that relation and you are braking the person, and hence God. DIO must be nimble enough to provide for the ‘dereliction’ of the Son, but also for the substantial unity with the Father, whilst also avoiding Patripassianism (the heresy that the Father suffers and dies on the cross).
  5. Ascension and Pentecost. This is an especially interesting instance of inseparable operations. The gospels seem to indicate something like a player substitution: the Son must depart in order for the Spirit to arrive. It is almost as if the Son and Spirit cannot both occupy the same space. This must be a false impression. Jesus promises to be with us forever. Somehow that presence takes place through the Spirit, however. How do we understand this ‘substitution’?
  6. Indwelling of the Spirit. Related to the previous question, we are temples of the Holy Spirit. Christ has ascended, yet he is also indwelling us (Rom 8:10, etc.). Why, then, does the NT speak primarily about the indwelling of the Spirit? In what way are we to understand that there is a unique indwelling of the Spirit, which is not simply the same thing as the presence of Christ, yet inseparable from it? The implications of working through this question bear on the relationship between justification and sanctification, but also on the question of the agency of the Spirit in the church. What is the significance of the bodily absence of Christ? May the Church, or believers, be regarded as continuations of the incarnation? Does the Spirit self-communicate himself to us in a way analogous to the self-communication of the Son to the human nature of Jesus? Finally, how is the indwelling of the Spirit now related to the ultimate seeing of God, the beatific vision?

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