The doctrine of the Trinity is once again on theology's front burner. Having languished under liberal theology, the doctrine is enjoying a resurgence of interest, as attested by the popularity of such works as Catherine Mowry LaCugna's God for Us and John D. Zizioulas' Being as Communion. We may also point to the importance of the doctrine to the theologies of Jürgen Moltmann, Eberhard Jüngel and Wolfhart Pannenberg as a testimony to its resurrection from obscurity.

Having taken note of this recent rise of interest in the doctrine, certain questions linger: Why has it lately sprung back to center stage? Why did theologians previously consign it to the irrelevant periphery? The easy answer to these questions – that only recently have theologians regained their senses and begun returning to theology's true source – not only begs numerous questions but also fails to explain the dynamics inherent in modern Trinitarian thought, dynamics that determine the fate of the doctrine in any given era. Such an explanation does not aid us in the task of understanding; understanding requires that we attend to the history of this thought.

My purpose in this book is to set forth the components of modern Trinitarian thought in such a way that its history – both distant and recent – becomes comprehensible. The thesis I propose is that modern Trinitarian thought is driven by three engines: the concept of the Word of God (i.e., revelation), the concept of reflective selfhood, and the concept of history.