In ancient times politics was encased in religion. It was believed that God revealed a law that governs the whole of human affairs. But then, argues Mark Lilla, at the transition to the modern age, a unique event occurred — a “Great Separation” — that pried politics away from theology. This took place along the North-Atlantic rim and Thomas Hobbes, more than anyone, articulated it. Lilla draws a portrait of Hobbes from an angle unfamiliar to many political theorists: By separating politics from theology, Hobbes founded not only the modern discourse of politics; he founded the discourse of modern, Western theology as well. This he did by directing focus away from God and zooming in on man: Hobbes cast theology as a discourse that discusses, not God, but man as a creature who believes in God.

Lilla's book begins with Thomas Hobbes — with how Hobbes, deeply disturbed by the passionate wars that washed across his England, disentangled the strands of politics from those of theology. Lilla then posits that Hobbes' separation was unstable. He shows, in subsequent chapters, how other thinkers wrestled with the Great Separation and how theological concerns regularly intruded upon Western political thought. Lilla also ends with Hobbes: He ends by suggesting that theological influences are on the upswing. Have we returned to a point where our politics again resemble those of ancient times?

Lilla navigates the tangled landscape of Europe's history of political ideas. He takes a simple and direct route. He points out novel sights along the way. He guides the reader through manageable, essay-like chapters. The book is beautifully written. It asserts that Western thinkers have always struggled with the triangular relationship of man, the world and God. The relationship between man and the world has been systematically stressed in the philosophical tradition of the secular West. God, however, has been long neglected. By reintroducing God, Lilla opens up for new ways to understand the Western tradition of modern political thought. What Lilla does with Hobbes in his first chapters, he does to other major contributors to the Western canon in later chapters: He brings out their theological side. He does this most convincingly with Rousseau and Kant (in Chapter 3, “The Ethical God”). He does it more controversially with Hegel (in Chapter 4, “The Bourgeois God). He does it most intriguingly with early twentieth-century scholars like Friedrich Gogarten, Franz Rosenzweig, Karl Barth and Ernest Bloch (in Chapters 5 and 6, “The Well-Ordered House” and “The Redeeming God”) — thinkers who are now nearly forgotten, but who once had great influence.

The chapters that discuss the twentieth-century authors constitute the most original parts of the book. They re-examine German scholars who, in the catastrophic wake of World War I, criticized the bourgeois theology of established thinkers. In their eagerness to replace the stillborn deity of the liberal theologians with a “redeeming God” of apocalyptic powers, they played straight into the hands of anti-liberal politicians. As a consequence, they helped fuel the growth of totalitarian politics in Germany and on the Continent.

It must be stressed here, that Lilla does not present the simplistic claim that religion was a driving force of fascism and communism in interwar Europe. Rather, he aims to demonstrate the resilience of theology in Western thought. The red thread of his book is the incomplete nature of Hobbes' Great Separation. Throughout the centuries theological concerns have kept intruding upon Western politics — the most unnerving challenges coming from thoroughly modern thinkers, on whom the unstable vapors of Gnosticism exerted a particularly strong influence, as his cases of Hitler-supporter Gogarten and the revolutionary Marxist Ernest Bloch suggest.

Lilla ends his book with a discussion of “the rebirth of political theology.” But this discussion is more a short summary of the book than a demonstration of an event.

This conclusion seems reasonable enough. In Europe, the recent debate about an European Union constitution brought forth arguments of political theology from some quarters. In the United States, theological concerns have intruded upon politics in recent years. But it is in the Middle East that the rise of political theology is most visible — in Israel's efforts to justify the Jews' right to a homeland and in Muslim criticism of the West. When the Iranian President, Mahmoud Ahmadinejad, criticized the United States in a letter to President Bush in the spring of 2006 and in a speech to the United Nation in the fall of 2007, he did so in terms of political theology. Indeed, on both occasions he applied anti-liberal and anti-democratic arguments that were eerily similar to those of Lilla's interwar Germans, Gogarten, Rosenzweig and Barth: He claimed that God has established a connection between Himself and the world, that liberalism violates the principles that govern His world and that democracy is an obstacle to His redemptive plans.

Lilla writes about Europe's past. Thus it is unfair to criticize him for avoiding a discussion of contemporary issues — especially since they open a Pandora's box of difficult and deeply controversial questions: Questions of political theology that have been flung onto the scene of contemporary European affairs mainly as a result of immigration from the Muslim world.

In the past, Europe's religious arguments were Christian and carried forth by various Protestant groups; but no more. Today, theological arguments in Western Europe do not emanate so much from churches as from mosques. Islam nurtures a political theology that Christianity lost centuries ago. This theology shapes the views of millions of people in the Muslim world. In addition, it shapes the lives of millions more who have immigrated to the West. These millions believe that God has revealed a law governing the whole of human affairs. However, they experience every day that their belief is unacceptable to the societies they live in. For the Western societies they have immigrated to are founded on Hobbes' principle of the Great Separation. These societies recognize no political claim that is based on divine revelation alone.

In this mismatch between Europe's secular politics and Islamic religious faith lie the major points of friction in contemporary Europe. Different European countries have adopted different strategies to cope with them — some countries forbidding religious symbols (like the head scarf) in public places, but others permitting them. This diversity of the responses to the theological challenge is itself a problem. However, the more basic problem is the inability to address the challenge properly. And this we cannot do unless we first recognize the deep discursive differences that separate the believing Muslims from the European societies they inhabit.

On first sight, Mark Lilla's learned book sharpens concepts and formulates arguments that may help us understand the chasm that divides the groups. On second thought, however, the book may be too limited to provide a deeper discussion of the relationship between theology and politics in the contemporary West. For the book discusses Protestant versions of the Christian tradition; it says little about other theologies. The book may, however, help diagnose the problem that informs a contentious issue of politics in the contemporary West.