The success of reductionism as a method in the natural sciences has heavily influenced modern theology, much of which attempts to reduce theology to other disciplines. However, the past few decades in science have shown the limitations of reductionism and the importance of emergence. The properties of complex systems with many constituents cannot be understood solely in terms of the constituent components and their interactions. I illustrate emergent properties and concepts with specific examples from geometry, condensed matter physics, chemistry and molecular biology. Emergence leads to a stratification of reality which affirms that ontology determines epistemology. To show the significance of emergence for the dialogue between theology and the natural sciences parallels are drawn with the theology of Karl Barth. The approach here is distinctly different from most writing on emergence and theology which embraces ‘strong’ emergence (which most scientists consider speculative), an immanent God and does not engage with orthodox Christian theology. Aspects of Barth's theology which are particularly relevant include his view that theology is an autonomous discipline which is not reducible to anthropology or history, the irreducible character of revelation, and the emphasis that ontology determines epistemology.

This article examines claims that Barth teaches the eternal subordination and obedience of the Son to the Father which some mainline theologians think leads Barth into the error of subordinationism. This reading of Barth has had a revival in recent times among socially and theologically conservative evangelicals who have found support in Barth for their thesis that, just as the Son is set under the authority of the Father, so too are women set under the authority of men. In reply I argue that Barth's stress on divine unity and on the full divinity of Christ and his explicit rejection of ‘every form of subordinationism’ makes this thesis untenable. When the evidence for this view is examined none of it proves the point. Rather, it highlights Barth's innovative and mind-expanding understanding of the triune God who is high and humble and of the Son who is forever both Lord and servant at one and the same time. However, this is not to say that Barth's doctrine of the Trinity is not without its problems.

In their remarkable new book, Christianity, Democracy, and the Radical Ordinary, Stanley Hauerwas and Rom Coles endorse a radical turn in our democratic practices and ecclesial engagements. In what follows, I say what this turn amounts to and consider what reasons might encourage churches and democracies to make it. In the end, I argue that good reasons are missing. We should forgo the radical and settle for just democracy, just church. In large measure, it is a dispute over Augustine's legacy as a social critic. Hauerwas and Coles accent the discussion of pagan virtue and temporal politics in the City of God while I prefer the remarks on idolatry and just love from book 4 of the Confessions. Hauerwas and Coles might share Augustine's anxiety about idolatry, but they resist his solution. He suspects that our idolatrous tendencies can be resolved only as we take on the just love of Christ, while they are inclined to think that democracy and church made radical will do the trick. They might also insist that their departure from Augustine on this matter is less than it seems, that they accent the radical in order to avoid unjust love, but I'm not convinced and in the end I bring in Plato's Alcibiades – garlanded, drunk and angry – to help justify my doubts.

The trinitarian theology of Gregory of Nazianzus is an important topic in patristic studies which is too often ignored by modern scholars. The aim of Beeley's book (like that of John McGuckin) is to deepen the study of this theologian who became very important for the later Orthodox tradition. Beeley wants to view Gregory not simply as one of the three Cappadocians or to make a short systematisation of the Theological Orations (or. 27–31), but rather to see his theology as a whole in its historical context. This makes the work an important contribution to historical studies in patristics, and I have learnt much from reading this book. The following remarks, even when critical, are intended to raise new topics for discussion, though controversial in some aspects.

If this very weighty and important book did nothing else than establish the fact for modern systematic theology that the trinitarian theology of the fourth century cannot be understood properly by dividing Eastern from Western theology with the usual statement that the former begins with the three persons and moves towards the divine unity while the latter begins with the divine unity and moves towards the three persons, then something truly significant would have been accomplished (Nicaea, pp. 52, 384). Why? Because then one would not be able to trace a supposed modalist tendency directly from Augustine through much Western theology to contemporary theologians such as Barth in order to argue for a view of God's triunity which actually could undermine the full divinity of each of the persons of the Trinity who in reality exist eternally as three persons, one being. Consider, for instance, the remark made by Ted Peters that ‘There is no inherent reason for assuming that the three persons have to be identical or equal in nature.’ If one studies the development of fourth-century trinitarian theology, I think one would find many reasons to insist that the three persons are in fact equal in nature, among which are that any other assertion would undermine the divinity of the Son, lead to some sort of subordinationism or adoptionism (what Barth called Ebionite christology), and would ultimately strip the Gospel of its saving power.

‘Radical Ordinary’ seemed like a good idea. The ‘ordinary’ is just, well, it is just so ordinary. No one is particularly attracted to the ‘ordinary’. But our lives are sustained by the ‘ordinary’. So maybe one of the ways to remind us of the significance of the ordinary is to qualify the ordinary by the word ‘radical’. A clever strategy that may, given Bowlin's response to the book Coles and I wrote, be far too clever.

It is not every day that one receives such a review of one's work! A colleague who heard these remarks delivered orally reminded me of the old saying that the next best thing to having a noble friend is to have a noble enemy, but I don't think it applies here. Volker Drecoll is hardly an enemy, although he does show some accomplishment at playing the role of the querulous friend! I am grateful to Professor Drecoll not only for travelling from Tübingen to attend the book review panel at the 2009 Society of Biblical Literature Annual Meeting in New Orleans, where this exchange first took place, but also for his lengthy and exacting challenge of my work.