In his 1983-4 Gifford Lectures, ‘In Search of Deity,’ John Macquarrie undertakes the breathtakingly ambitious project of outlining a coherent natural theology which addresses the pressing needs of ethics, theology, religious experience, and ecclesiastical life. The lectures begin with some crucial prolegomenal ground-clearing, as Macquarrie seeks to vindicate natural theology against Humean and Kantian objections, contending that such modern critiques are based upon a faulty view of God as unqualifiedly transcendent and disjointed from the world. This insight provides the uniting centre of the lectures, as Macquarrie repeatedly exposes an incipient malady infecting both classical theism and atheism; their shared conception of God as ‘just another object in the world,’ coupled with a failure to recognise the dialectical character of God’s relation to finite reality. According to Macquarrie, this mistaken conception of the God-world relation engenders insoluble deficiencies within atheism, pantheism, and classical theism, which collectively provide the foil against which Macquarrie outlines his own conception of deity, 'dialectical theism'. Dialectical theism seeks to avoid both the utterly transcendent, monarchial God of classical theism, who exists serenely unperturbed by a finite reality which is therefore dispensable, and a pantheistic conception in which deity is absorbed into the world-process, rendering God impotent, haplessly carried along in history’s unfolding. In contrast, Macquarrie introduces six dialectical oppositions within deity, which are founded, firstly, in a searchingly pursued natural theology, and secondly, in reflection upon the ontological preconditions required by the mysterious and ecstatic character of reality attested to in the religious/mystical consciousness. There is a dialectical contrast between being and nothing, which insists that God is not another object in the world, and therefore does not ‘exist’ in the normal sense, but rather is the source of beings who is beyond being. There is a dialectical opposition between the one and the many, expressed in a natural theology of tri-unity, in which deity includes a primordial ineffable dimension, a ‘coming forth’ incarnational dimension, and a unitive dimension, expressed in the eschatological returning of all reality to its transcendent source in deity. A dialectic between knowability and unknowability expresses deity’s ineffable, transcendent aspect, alongside its intelligible presence within all things. This dialectic reflects a related opposition between God’s non-anthropomorphic impersonal depth, and his personal expression and representation in creation. The dialectic between impassibility and passibility speaks to God’s participation in the world process, as he finds expression and extension within it, while simultaneously retaining his transcendent identity and omnipotent capability. Most crucially, there is the final dialectic between immanence and transcendence, in which God as source remains beyond the world, while still being expressed and entirely present within it. Macquarrie patiently grounds and unfolds this conception of deity through dialogue with, and critique of, various figures whom he locates within a broad tradition of dialectical theism. These include Plotinus, Pseudo-Dionysius, John Scotus Eriugena, Nicholas of Cusa, Leibniz, Hegel, Whitehead, and Heidegger. In all, Macquarrie exhibits a breathtaking confidence in the breadth and capacity of natural theology, combining speculative reason and mystical spirituality to construct a universalised, ahistorical conception of God, finding within this natural theology an account of a triadic, incarnate deity who, conceptually unites the diversity of the major world religions. It is a consummate understatement to register that few will wholeheartedly embrace all the details of Macquarrie’s account, but one cannot but marvel at the scope, audaciousness, and abandonment with which he pursues his vision. This is natural religion fearlessly pursued to its utter extremity.