Update: I originally wrote this series of posts in 2015 and since then I have changed my view. I’ve decided to keep the posts live, but wish to add that caveat at the outset.
In the previous post I laid out some preliminary comments on the debate surrounding the idea of the Eternal Functional Subordination of the Son to the Father. In this second post, I consider the relationship between the Economic and Immanent Trinities.
The Economic and Immanent Trinities
Early Trinitarian theology focused on what would later be called the ‘economic Trinity’; the Trinity in relation to the world. It was Origen who began to develop the idea of the ‘immanent’ or ‘ontological’ Trinity, which refers to God present to himself in eternity. The distinction was further carved out by the Cappadocian Fathers, who considered it necessary for preserving the transcendence of God and resisting Modalism, which tied the Trinity exclusively to history.
The twentieth Century saw renewed interest in Trinitarian theology. Rahner, keen to rescue the doctrine from possible theological irrelevance, wrote his famous axiom: ‘The “economic” Trinity is the “immanent” Trinity and the “immanent” Trinity is the “economic” Trinity.’
This phrase became ‘virtually an item of orthodoxy’ but is susceptible to misinterpretation. Some have read Rahner as removing all distinction between the immanent and economic Trinities, but it is doubtful whether Rahner intended so radical an application. Rightly understood, Rahner reminds us that God is not other than his self-revelation in history, but as Giles notes, ‘it does not follow that this historical revelation comprehensively reveals the triune God as he is apart from history.’
We must avoid fully conflating the immanent and economic Trinities. A distinction is heuristically and theologically useful for maintaining the proper distance between Creator and Creation and ‘recognising that creation is contingent rather than necessary, yet that the divine persons are freely involved in worldly action.’ But we must not overstate the distinction, giving the impression of contradiction between God-in-Himself, and God as He interacts with the created order.
The immanent Trinity, insomuch as it concerns God in eternity, is logically foundational for the economic Trinity, yet we do not have access to explicit detail of the immanent Trinity. Van Til’s claim that, ‘We must always think first of the ontological Trinity before we think of the economical Trinity’ proves therefore impossible. Divorcing Trinitarian reflection from economic revelation isolates it in the realm of metaphysics, and goes beyond where reason and Scripture can take us, thus making it seem irrelevant and returning to the error of Catholic scholasticism that Rahner sought to correct.
We must admit, with Rahner, that ‘Scripture does not explicitly present a doctrine of the “immanent” Trinity.’ Nor could our minds adequately grasp it, since it would require us to think outside the space-time continuum. We therefore have no choice but to think of the immanent Trinity through and beyond the oikonomia as revealed in Scripture, recognising that ‘all speculation of what God is like in transcendent otherness is perilous even with the only sure foundation of the Bible.’
I presuppose that the economic revelation of the triune God corresponds truthfully with His existence in eternity. That is, nothing revealed in the economy will contradict the truth of the immanent Trinity. The faithfulness of God requires that He reveal Himself in a manner that truthfully reflects who He is. ‘A bifurcation between the economic Trinity and the immanent Trinity undermines our knowledge of God. Our salvation depends on God’s revelation of himself in the history of salvation being true and faithful to who he is in himself.’ But whilst wholly truthful, the oikonomia is by no means the whole truth and cannot be said to exhaustively describe the triune God as He is eternally. ‘While theories of the immanent Trinity will not simply duplicate the economic Trinity, they will reflect the economic Trinity in an embracive macrostructure that is faithful to God’s Word.’
How does this excursus relate to our central question? Giles writes, ‘What divides evangelicals today on the economic-immanent Trinity issue is whether the subordination of the Son seen in the incarnation is to be read back into the immanent Trinity?’ Non-Subordinationists answer in the negative, arguing that the subordination of the Son to the Father ‘was an interim or temporary state. It was not, nor shall it be, an eternal condition.’ Indeed, Bilezikian calls Jesus’ incarnation ‘a task-driven temporary phase of ministry.’ This is problematic, since it implies that the Son in the oiokonomia may not truthfully reflect how he is in eternity. Letham’s charge is a pertinent one. If the Christ we see in the gospels is only a ‘temporary appearance’ and ‘does not reflect the eternal Son as he is’ then are non-Subordinationists not in danger of Modalism?
Del Colle concludes,
The soteriological principle essentially means that what God is in his saving activity is what God is in the divine being itself. Anything less would compromise the nature of divine revelation and the communion of grace that is constitutive of Christian life and community. Second, in the revelatory events of the sending of Jesus Christ and the outpouring of the Holy Spirit there clearly exist dialogical relations of Christ and the Spirit to the Father and to each other. The presumption in favour of such relations in the immanent being of God is strong if we are not to violate our first principle.’ 
 Giles, (2006) p249; Allison, (2011) p237
 Olson, (2011a)
 Rahner, (1970) p22
 Olson, (2001a)
 See Volf (1998) on Hegel p216, Horton, (2011), p301, Torrance, ‘The Trinity’ in Webster (2000), p73-74 and McCormack ‘Grace and Being’ in Webster (2000) p100-101
 Giles, (2006) p252. Emphasis added.
 Horton, (2011) p330
 See Carson, (2000) p59
 See Letham’s (2004) critique of Pannenberg and Moltmann, p298-321
 Quoted in Giles, (2006) p257
 Del Colle, ‘The Triune God’ in Gunton (1997) p137, Horrell (2004) p416; Letham, (2004) p362-364
 Rahner, (1970) p22
 Ibid., p22
 See Davies, (2001) 258-259
 Gunton, (1991) p137
 Horrell, (2004) p414
 Letham, (2004) p296
 Horrell, (2004) p418
 Giles, (2006) p263
 Bilezikian, (1997) p59
 Ibid., p61
 Letham, (2004), p484
 Del Colle in Gunton (1997) p137-138