The God Who Acts

Two terms organise everything in this lesson. The economic Trinity means God as he acts in the history of salvation: the Father who sends, the Son who is sent and becomes man and dies and rises, the Spirit who is poured out at Pentecost and dwells in the church. The word comes from the Greek oikonomia, the administration or management of a household, which the Fathers used for God's ordered plan carried out in time. The immanent Trinity means God as he is in himself, eternally, whether or not there had ever been a world. The Greek Fathers called that theologia, the doctrine of God in himself, as distinct from the oikonomia.

Everything the church knows about the second, it learned from the first. Nobody deduced the Trinity from the concept of God. The apostles met the Son, received the Spirit, and reasoned back. So the relation between the two is not an idle question: it is the question of whether what we met in Jesus and at Pentecost is really what God is, or only how he chose to appear to us for a while.

Karl Rahner put that with a sentence that has been quoted more than any other in twentieth-century trinitarian theology. In his 1967 treatment of the subject, translated into English in 1970, he wrote that the economic Trinity is the immanent Trinity and the immanent Trinity is the economic Trinity. The context matters. Rahner's complaint was pastoral before it was technical: he judged that Christians had become, as he put it, almost mere monotheists in their practical life, and that the doctrine had been isolated from everything else in theology by the arrangement of the textbooks, which treated the one God first and the triune God afterwards, as a separate subject. His rule was meant to weld the doctrine back onto the gospel. If God as he meets us is God as he is, then the doctrine is not a puzzle appended to Christianity; it is a description of what happened.

The rule has been enormously influential across the traditions, and the first half of it is now close to universally accepted. God does not deceive; what is revealed in the missions of the Son and the Spirit really discloses the eternal relations. The objections attach to the second half, the converse, and they are serious.

The first objection is about God's freedom. If the immanent Trinity simply is the economic Trinity without remainder, then God's being seems to include his relation to this world, and creation stops being free and becomes necessary to God's being who he is. Jurgen Moltmann pressed the rule in that direction deliberately, arguing that the cross is an event in God's own life, and Robert Jenson went further, holding that God's identity is constituted by the history of Jesus of Nazareth. Paul Molnar's Divine Freedom and the Doctrine of the Immanent Trinity, published in 2002, argues that this line of development dissolves the distinction that makes grace grace: if God needed the world to be himself, then his love for the world is not gift but necessity. Yves Congar, writing on the Spirit, accepted the first half of the rule and held that the converse needs careful qualification, which has become a common position.

The second objection is about how much we may infer. If every feature of the economy maps directly onto the eternal relations, then the Son's obedience, his growth in wisdom, his ignorance of the day and the hour, and his death all have to be projected into the immanent Trinity, which nobody wants. The standard answer is that the missions reveal the eternal processions without the created effects being read back into God, but stating the rule for what transfers and what does not is exactly the difficulty, and it is the unresolved core of the argument reported in the previous lesson about eternal subordination.

Rahner's defenders reply that he was not claiming that the two are identical in every respect, only that the same God is in question and that there is no hidden fourth thing behind the three we have met. Read that way, the rule is a rule against a God who keeps his real self back, and it is hard to object to. Fred Sanders's study of the axiom argues that much of the debate has been conducted over rival uses of the word 'is'. What a student should carry away is the distinction itself, which is indispensable, together with the knowledge that how tightly to bind the two sides is a live question among people who all affirm the creed.

Christians habitually assign the world to the Father, the cross to the Son and the church to the Spirit. That habit is licensed by the tradition and it is also hedged by the tradition, and the hedge is what this section is about.

The principle is Augustine's, and the tag by which it is usually quoted is later and scholastic: opera Trinitatis ad extra sunt indivisa, the external works of the Trinity are undivided. Augustine's own formulation, at the start of De Trinitate, is that the Father and the Son and the Holy Spirit work inseparably. The argument for it is straightforward once the previous lesson is in place. Action follows from nature, and the three have one nature, wholly and without division. If the Father could act where the Son does not, the two would have separate powers, and separate powers means separate natures, and separate natures means two gods. So whatever God does towards what is outside him, all three do.

The scriptural warrant is better than students expect. Creation is by the Father in Genesis 1, through the Son in John 1:3 and Colossians 1:16 and 1 Corinthians 8:6, and with the Spirit hovering over the waters and renewing the face of the ground in Psalm 104:30. The raising of Jesus is attributed to the Father in Galatians 1:1, to the Son in John 2:19 and 10:18, and to the Spirit in Romans 8:11. Indwelling is the Spirit's in Romans 8:9, the Son's in Ephesians 3:17, and in John 14:23 the Father and the Son together come and make their home. The pattern is not carelessness. The writers attribute the same work to each of the three because the same God is doing it.

Appropriation is what makes the habit legitimate. Certain common works are attributed especially to one person because there is a fittingness between the work and that person's distinguishing property: creation to the Father because he is the source without source, redemption to the Son because it is he who became man, sanctification to the Spirit because he is the gift and the bond. An appropriation is not a division of labour and it is not arbitrary either. It is a way of speaking that follows the shape of the eternal relations, and it is exactly how the creed itself speaks, which is why the creed can assign the making of heaven and earth to the Father in one article and say in the next that all things were made through the Son.

Then the obvious objection, which the inquiry asked you to state before reading: if all three always act together, how did only one of them become man? The classical answer distinguishes the act from what the act terminates on. The whole Trinity effects the incarnation, the Father sending, the Spirit overshadowing, the Son assuming; but only the Son assumes the human nature to himself, so only he is the one who is born and suffers. Aquinas puts it exactly that way in the third part of the Summa. The same distinction carries the baptism scene in Matthew 3, where three are plainly doing three different things and the tradition declines to say that three separate agents are at work. Whether that distinction is a solution or a restatement is a fair question, and it is put to classical theology regularly.

Karl Barth made a related complaint from another direction. He was concerned that inseparable operation, pushed hard, flattens the distinctness of the persons in the economy to a set of labels, and he built his own doctrine around God's self-revelation as Revealer, Revelation and Revealedness, preferring to call the three modes of being, Seinsweisen, rather than persons, on the ground that person now carries a modern sense of a separate centre of consciousness. Rahner independently preferred distinct manners of subsisting for the same reason. Both were accused of modalism, both denied it, and both denials are worth taking seriously: neither man thought God merely appears in three ways. But the accusations show how narrow the path is. Guard the unity and you are called a modalist; guard the distinctions and you are called a tritheist. Which brings us to the models.

There are two broad ways of holding the doctrine together, and every theologian in the tradition is somewhere on the line between them. Neither is a heresy. Each has a heresy immediately next door, and knowing which one is next door to your own instinct is a large part of theological maturity.

The psychological model starts from the one God and looks for threeness in the life of a single mind. Its founding text is Augustine's De Trinitate, with its triads of memory, understanding and will, and its great systematic development is Aquinas, for whom the Son is the Word that the divine intellect eternally speaks and the Spirit is the Love that the divine will eternally breathes. That is not a metaphor dropped in from psychology; it is an attempt to say what kind of processions could occur in a simple, immaterial God, given that begetting and breathing cannot mean in God what they mean in bodies. In modern form the approach is represented by Karl Barth and Karl Rahner, and among analytic philosophers by Brian Leftow, whose essay on a Latin Trinity argues that one God can live three life-streams without becoming three beings.

Its named danger is modalism, the position of Sabellius in the third century and of the various monarchians: that Father, Son and Spirit are three ways in which one divine person presents himself, three masks or three successive roles, so that the one who is the Father in creation is the Son on the cross. It is called Sabellianism in the West and the church rejected it early and everywhere. The reason it is the danger of this model is structural: if you begin from one subject and find the three inside its operations, you are one short step from three aspects of one subject, and the step can be taken without noticing. The conversational test is simple and it catches this every time. If the three are modes of one person, who was Jesus praying to in Gethsemane, and why did the answer not come from inside him?

The social model starts from the three and asks what makes them one. Its advocates are numerous and prominent: Jurgen Moltmann, whose The Trinity and the Kingdom in 1980 argued from the cross and against what he saw as the political consequences of divine monarchy; John Zizioulas, whose Being as Communion made personhood prior to substance; Leonardo Boff, who drew liberationist conclusions; Miroslav Volf, whose After Our Likeness in 1998 argued from the Trinity to the shape of the church; Cornelius Plantinga Junior; and, in analytic philosophy, Richard Swinburne, David Brown and William Hasker. They appeal to the plainly interpersonal language of scripture, to the Son's prayer to the Father, to the mutual love of John 17, and to the Cappadocian emphasis on the three hypostaseis, and they argue that the unity is secured by perichoresis and by the Father's monarchy rather than by a single divine consciousness.

Its named danger is tritheism: three gods who get on well. The criticism has come from several directions. Brian Leftow's essay against social trinitarianism argues that the proposals on offer either do not deliver three genuine persons or do not deliver one God, and that appealing to perichoresis at the crucial moment names the problem rather than solving it. Karen Kilby's 2000 article on perichoresis and projection makes a sharper and more uncomfortable charge: that social trinitarians project a favoured model of human community onto God, describe it in trinitarian vocabulary, and then commend it back to the church as though it had been learned from revelation, so that the doctrine becomes a mirror. Stephen Holmes's The Quest for the Trinity in 2012 argued that the whole twentieth-century trinitarian revival, social models included, departed from what the church had actually taught for most of its history.

The historical claims on both sides need watching. Social trinitarians often present themselves as recovering the Cappadocian East against a distorted Latin West, and that framing rests on the nineteenth-century contrast the previous lesson described, which specialists have largely abandoned. Sarah Coakley has argued in detail that Gregory of Nyssa's treatise On Not Three Gods, the text most often cited for a social reading, is doing something other than what modern social trinitarians want it to do. On the other side, defenders of the social approach reply that the criticism of projection cuts both ways, since a model built on the operations of a single mind is also drawn from somewhere, and that the fear of tritheism has historically done more to suppress the plain interpersonal language of the Gospels than the fear of modalism has done to suppress anything.

Where does this leave a student who has to teach? With a discipline rather than a verdict. Say the four things the church has actually settled and hold them all at once: there is one God; the Father, the Son and the Spirit are each fully that God; they are really and eternally distinct; and they are not three gods. Any account that drops one of those has failed, and the two models are attempts to hold all four with different points of departure, not rival religions. And be honest about the cost of your own instinct. If you find the interpersonal language natural, you are at risk of three; if you find the unity obvious, you are at risk of one; and the person who thinks he is at risk of neither is at the greatest risk of all.

Now the question the module has been building towards, answered from texts rather than from sentiment. What is different, in practice, if this is true?

Prayer first, because it is where the doctrine is least abstract. Ephesians 2:18: 'For through Him we both have access to the Father by one Spirit.' The Greek word rendered access is the word for being brought in and introduced, used of admission to a presence you had no standing to enter. The sentence names all three, and each has a different position in it: the Father is approached, the Son is the way of approach, the Spirit is the one by whom, or the sphere in which, the approach happens. The BSB takes the first sense ('by one Spirit'); the Greek preposition en also carries the second ('in one Spirit'), and many translations print that, as you can see on Bible Hub. The lesson's point holds on either reading: the Spirit has a distinct place in the approach, and the sentence cannot be said without all three. That is not decoration. It is an answer to the question of how a guilty person can pray at all. Romans 8:15-16 adds the subjective side: 'you received the Spirit of adoption to sonship, by whom we cry, "Abba! Father!"' and 'The Spirit Himself testifies with our spirit that we are God's children.' Galatians 4:6 says the same from the other end, that God sent the Spirit of his Son into our hearts crying Abba. And Romans 8:26 covers the case that matters most: when you do not know what to pray, the Spirit intercedes with 'groans too deep for words'. So the Christian at prayer is not a petitioner shouting at a distant throne. He is carried to the Father by the Son and in the Spirit, and when he has nothing to say the praying continues inside him without him. This is why the historic collects of East and West are almost all addressed to the Father, through the Son, in the Holy Spirit. The grammar of the church's prayer is the doctrine in use.

Worship second. Matthew 28:19 baptises into a single name held by three, which is a liturgical act before it is a theological claim, and it is the act by which every Christian enters the church. 2 Corinthians 13:14 blesses a fractious congregation in three names. John 5:23 makes it a test: that all may honour the Son just as they honour the Father, and whoever does not honour the Son does not honour the Father who sent him. And Revelation 5:13 puts praise and honour and glory and power on him who sits on the throne and on the Lamb together, in a book that twice has an angel forbid the seer to worship him. Set those beside Isaiah 42:8, where God will not yield his glory to another, and you have the reason the fourth century could not compromise. If the Son is not God, the church's worship has been idolatry from the first week. Basil's argument in On the Holy Spirit works in exactly this direction: the Spirit is glorified with the Father and the Son in the church's doxology, and only God is glorified, so the Spirit is God. The practice came first and the doctrine was drawn out of it.

Salvation third, and this is where the doctrine stops being a topic and becomes the shape of the gospel. Read Ephesians 1:3-14 as one sentence, which in Greek it very nearly is. The Father blesses, chooses before the foundation of the world, and predestines to adoption. In the Son there is redemption through his blood and the forgiveness of trespasses. The Spirit is the seal and the pledge of the inheritance. Three movements, one salvation, and every stage ends with the praise of the Father's glory. Titus 3:4-6 makes the same shape compact: God our Savior saved us, in the BSB's words, 'through the washing of new birth and renewal by the Holy Spirit', the Spirit he 'poured out on us abundantly through Jesus Christ our Savior'. 1 Peter 1:2 opens a letter by saying that its readers are elect according to the foreknowledge of God the Father, sanctified by the Spirit, for obedience to Jesus Christ and sprinkling by his blood.

What that rules out is worth stating because it is a live pastoral problem. It rules out the picture, common in popular preaching and never in a creed, of an angry Father placated by a loving Son. In that picture the Father and the Son want different things, which is tritheism with a cross in it, and it makes the atonement an internal dispute in the Godhead. The texts say the opposite: 'God so loved the world that He gave His one and only Son' (John 3:16); 'God proves His love for us in this: While we were still sinners, Christ died for us' (Romans 5:8); 'God was reconciling the world to Himself in Christ' (2 Corinthians 5:19). The cross is not something done to God to change his mind. It is something God does, all three of him, and the inseparable operations rule of the last section is what protects that.

And it rules out the reverse error of treating the three as interchangeable, which empties the Christian's actual experience. The believer does not relate to a generic deity. He is adopted by a Father he did not have, united to a Son who is his brother and his priest, and indwelt by a Spirit who is God inside him and not an influence. Those are three different relations and scripture describes them differently. A Christianity that loses the distinctions loses the adoption, the mediation and the indwelling all at once, and keeps only a word.

At the start of this module you could read a passage in its own context and say what genre it was. What you could not do was say what the whole Bible teaches about God and defend it. Take stock of what has changed, because the list is longer than it feels from inside.

You can state the Creator and creature distinction and show why it makes every word about God a stretched word, and you can explain analogy, univocity and equivocity accurately enough that neither a Thomist nor a Scotist would wince. You can present apophatic theology as a discipline rather than a mood. And you can give the essence and energies distinction as an Orthodox believer would give it, with the problem it was built to solve and the Latin objection to it, which very few Western graduates can do. If you live in a country where most Christians are Orthodox or Catholic, that alone will change how you are heard.

You can teach the attributes without turning them into a list of adjectives. You know that the filing scheme is itself an argument. You can handle Exodus 3:14 honestly, including the awkward fact that the identical Hebrew form two verses earlier is translated as a promise, and you know to teach aseity from Acts 17:25 and John 5:26 instead. You can state divine simplicity as its defenders state it and then give Plantinga's and Mullins's objections at full strength, and say truthfully that the argument is unfinished. You can put 1 Samuel 15:11, 29 and 35 in front of a class and make them sit with it before you offer anybody's solution.

You can show where the doctrine of the Trinity comes from in scripture without pretending it is written on the surface. You know which texts are contested and why: the punctuation of Romans 9:5, the Granville Sharp construction behind Titus 2:13, the vocative at Hebrews 1:8, the rare noun in Philippians 2:6. You can give away the Johannine Comma cheerfully and still make the case. And you can say the honest sentence out loud, that no verse states the doctrine and that it is a conclusion drawn from the whole, and then show why that is the stronger position rather than the weaker one.

You can tell the story of the fourth century without a cartoon in it. You can say what Arius actually taught and why it took fifty-six years and five exiles to answer him, why a non-biblical word was needed, and what the Homoians and Homoiousians and Anomoians were each trying to protect. You can explain why the Greek and Latin words for person and substance kept producing false accusations of heresy in both directions. And you can lay out the filioque, its route into the Western creed, the theological case on each side, and the fact that Rome itself held the Eastern position on the text for two centuries, without turning it into a story with a hero.

Finally you can answer the question the module opened with, which was whether God can be known. The answer that the whole module has been working towards is that he cannot be comprehended and he can be known, because he has spoken and because the Son has made him known, and that the knowing is not an achievement but a gift with a shape: to the Father, through the Son, in the Spirit. That shape is not a formula to be recited at the end of prayers. It is what is happening when a Christian prays at all.

One thing to carry out of the module, and it is a warning. This is the part of theology where a teacher's tradition leaks in hardest, because these are the doctrines his own church settled long ago and no longer argues about. If you found yourself, at any point in these five lessons, unable to state one of the positions in a form its own defenders would recognise, that is the position you should read next, and you should read it in a book written by someone who holds it. The bar for this course is not that you agree with your teachers. It is that when you stand in front of a divided church, the people who disagree with you can tell that you have understood them.