Unlike (as far as I can tell) most of my con temporaries, I listened to a great many sermons earlier in life, usually based on the Bible. They were a curious experience. Through all my vicissitudes of belief and unbelief, the words of Scripture never lost their majesty and beauty. The commentary was another matter, however. Sometimes — from Franciscan parish priests, for example — it was earnest, practical and commonsensical to the point of banality. Other times — typically from university chaplains or visiting Jesuit ____ — it was cerebral, hip and sophisticated to the point of implausibility: what my ‘60s peers and I used to call, with mixed admiration and frustration, a “head trip.” Jack Miles, now an editor at the “Los Angeles Times”, is a former Jesuit and student of Near Eastern languages in Rome, Jerusalem and at Harvard. So it’s no surprise that his subtle learned, gracefully written study of God as He is portrayed in the Old Testament is a frequently dizzying, sometimes exhilarating head trip.

What kind of book is this, exactly? In his “Summa Theologica,” St. Thomas Aquinas set about defining God by negation: “If we cannot directly say what His essence is, we can at least endeavor to ascertain what it is not.” It’s comparatively easy to say what “God: A Biography” is not: It’s not a piece of historical or philological research (though there’s plenty of scholarship behind it); not a work of theological speculation; and not quite literary criticism, since it is scarcely concerned with formal means or aesthetic effects. Nor, of course, is it a biography in the usual sense; the ratio of fact and interpretation is utterly different, not to mention the ontological status of the subject. “A psychological study of a fictional character” is perhaps the least misleading definition; though naturally, applied to God and the Bible, this takes some explaining.

The Bible has always been esteemed for its literary merits, but usually only in passing, since its overriding importance was as a guide to conduct and belief. In a secular age, though, it can be and has been approached with primarily literary and psychological questions in mind. Miles’ questions are: If we consider the Old Testament purely as a literary text — a novel or an epic poem, say — with Yahweh as its protagonist, how would we describe Him? What are His motives? Does He change, and how? Does He bear any significant resemblance to other figures in the culture of His time or of subsequent times?

Miles pursues these questions through each book of the Old Testament in turn. (He uses the Jewish version of the Old Testament, the “Tanakh,” not for the sake of its historical priority but because its different arrangement yields a different, arguably more coherent and poignant portrait of Yahweh.) What he finds is that God experiences not just pleasure or displeasure in His dealings with mankind but surprise, ambivalence, regret, yearning, anxiety, even contrition. There seems to be more than one divine persona: a High God, the remote Creator and Destroyer, and a personal deity, who notices individual suffering and bestows favors, as well as echoes of several contemporary Near Eastern divinities. The nature of His covenant with Israel alters, from a primitive, obsessive concern with fertility and racial purity (which the Israelites chronically neglect, resulting in defeat, massacre and exile) to a more emotionally complex and inclusive relationship with a largely ethical basis.

It is not merely, Miles suggests, that God presents Himself differently according to the occasion or the capacities of His listeners. Rather, God Himself changes. “After each of his major actions, he discovers that he has not done quite what he thought he was doing, or has done something he never in tended to do. He did not realize when he told mankind to “be fertile and increase” that he was creating an image of himself that was also a rival creator. He did not realize when he destroyed his rival that he would regret the destruction of his image. He did not realize that his covenant with Abraham, the reconciliation of such contrary urges within his own character, would require him “to go to war with Egypt. He did not realize when he went to war with Egypt that his victory would leave him with an entire people on his hands and would require him to be come a lawgiver for them and conquer a land for them to live in.” And so on through the prophets, Psalms and Proverbs.

The capstone of Miles’ “biography” is his account of the Book of Job. A very great deal has already been written on this subject; yet in 25 masterly pages, intimately connected to the rest of the book but capable of standing alone, Miles shows that this “profoundly blasphemous story” of a Capricious God and an unyielding man is a turning point in humankind’s spiritual development and, in effect, the climax of Yahweh’s life.

“God: A Biography” is a remark able book: a marvel of ingenuity, discrimination and erudition. Still, it left me a bit disgruntled. The experience of reading the book — of following Miles’ dense and intricate but always lucid arguments — is far more satisfying than the result: a psychologized God, fashioned in the image and likeness of man (and, of course, woman) and characterized in the language of late-20th-century humanism. If God has “urges” and “inner conflicts,” if He is “volatile, and prone to dark regrets and darker equivocations,” if He is “lonely,” “suffering,” and “in distress,” I’m not sure I want to know about it. We all have our problems. Human psychology is, if not altogether a bore, at any rate not so in exhaustibly interesting as Miles seems to believe.

“The God of Abraham, of Isaac and of Jacob, not the God of the philosophers and theologians,” admonished Pascal. Myself, I prefer this God of the philosophers and theologians. The God of Plato and Aristotle, of Plotinus and Augustine, of Aquinas and Bonaventure, of Newman and C. S. Lewis; the eternal immutable, infinite, ubiquitous, omnipotent, omniscient Supreme Being, Unmoved Mover, ens realissimum, whose existence is identical with His essence and who is without body, parts, or passions, is one of the sublimest achievements of the human imagination. He, not Yahweh, is the deepest mystery, for metaphysics (as His reluctant admire Nietzsche pointed out) is the subtlest psychology, the supreme fiction.