Interested in a crash course on religion and international politics? Consider these two books, one for a broader audience of the unconvinced, the other for academic specialists in the area.

In God's Century, three established scholars pool their expertise to provide some high-altitude reconnaissance. The first three chapters make the case for a “global resurgence of religion.” Chapters 4–7 look at the role of religious actors in democratization, terrorism, civil war, and peacemaking. The concluding chapter enumerates 10 “rules” for policy analysts. The high-altitude strategy has predictable pros and cons: The book surveys half a millennium of history and zigzags across the globe, but paints with a very broad brush and covers some areas and topics better than others.

Chapter 1 is addressed to the skeptic. It launches a barrage of evidence that religion really does matter. Chapter 2 deals with how it matters. It argues that two factors are key: how religious actors think about politics (their “political theology”) and how religious and political “authority” are related: Are they institutionally independent or integrated? Are their interactions characterized by consensus or conflict? In Madisonian fashion, the authors argue that independence and conflict lead to more desirable outcomes than do integration and consensus. In Chapter 3, they provide a simple narrative of religion and politics worldwide from the Middle Ages to the present. A premodern period of “friendly merger,” they say, gave way to a “friendly takeover” of religious life by consolidating states, beginning around 1500, followed by a “hostile takeover” by secularizing states, starting with the French Revolution. Religious politics then reemerges during the second half of the twentieth century for a variety of reasons, including the failure of secular “isms,” the spread of electoral democracy, and improvements in communication technology.

The middle chapters apply the analytical framework from Chapter 2 to substantive problems. In Chapter 4, the authors argue that religious actors played some role in 48 of 72 cases of “substantial democratization” since 1972, and a “leading role” in 30 of them. Religious actors were most likely to play such a role when they enjoyed considerable “independence” from political authorities and when they espoused a “democratic political theology.” What about religious terrorism, the subject of Chapter 5? It arises out of conflicts over “integration,” when one religious actor is integrated with political authority and another, excluded religious actor embraces an integrationist political theology. By contrast, civil wars, the focus of Chapter 6, arise more often when an authoritarian regime launches a secularizing campaign, excluding religious actors from public life, thereby fomenting backlash and enabling extremists. Religious civil wars of this sort have become increasingly common since 1940, they claim, and have been more severe than secular civil wars during this period.

In Chapter 7, finally, the authors examine the role of religious actors in peace and reconciliation processes. In keeping with their general line of argument, they contend that the likeliness and effectiveness of such efforts are greatest where the religious actors enjoy substantial independence from political leaders on both sides of the conflict and advance a pro-peace political theology. The concluding recommendations in Chapter 8 are tacitly addressed to the sort of “hard-power” political realists who tend to see religion as a sideshow or a nuisance. They are urged to take religious actors more seriously, though not too seriously, and to see the promotion of religious freedom as means for improving security.

Any book that covers this much ground in just over 200 pages will necessarily oversimplify, omit, and undertheorize certain themes, and God's Century is no exception. As regards oversimpflication: The “friendly takeover” moniker fits Lutheran Europe better than Catholic Europe, and Catholic Europe better than Calvinist Europe. The “hostile takeover” label, in turn, best fits France and hardly fits America. As David Martin and others have shown, the confessional settlements of the Reformation era were highly variable and set the parameters for the secular settlements of the modern era, which were also highly variable. If the relationship of religious and political authority is as consequential as the authors believe, then describing and explaining such variations and path dependencies is crucial. Concerning omission: Despite its purported significance, “political theology” remains little more than a dummy variable, coded as “democratic” or “pro-peace” or not. Very little is said about the inner logic or dynamics of political theologies, about how and why a particular politics becomes conjoined with a particular theology in a particular way.

Finally, a propos of undertheorization: While the book's predictions are often confirmed, empirical anomalies are also readily at hand. Why did the secularizing programs in the French Third Republic or Kemalist Turkey not lead to civil wars? Why has there not been more terrorism within Saudi Arabia? No doubt, the authors would have answers to such questions, but they do not follow immediately out of the book. The answers would require greater attention to standard variables like state capacities, political parties, intellectual elites, and so on.

The bottom line: The book provides a solid introduction for nonspecialists, students, and the educated public, but contains few surprises for those who are already versed in the field of religion and politics.

Where Andrew Phillips's new book is concerned, the reverse is more nearly true: War, Religion and Empire will appeal mainly to academic specialists in international relations and kindred fields but would be pretty rough sledding for most everyone else.

This book poses three questions: “What are international orders, what accounts for their transformation, and how can they be preserved?” (p. 1). Drawing on and synthesizing constructivist and realist approaches, Phillips defines international orders as “the constellation of constitutional norms and fundamental institutions” that underwrite security and cooperation (p. 5). They have both an Aristotelian and an Augustinian moment: They are oriented toward some conception of the common good but employ violence and coercion to restrain their subjects—and protect the dominant. They are suboptimal equilibria. International orders collapse “when they experience systemic legitimacy crises occasioned by a combination of institutional decay, disruptive military innovations, and ideological shocks” (p. 43). Collapse is followed by anarchy and often by attempts at imperial consolidation. The emergence of a new order is a slow and piecemeal process marked by the crystallization of new rules and new actors.

Consider the case of Latin Christendom. Its “normative complex” was constructed out of Christian ethics, soteriology, and political theology, while its fundamental institutions comprised the “papal-imperial diarchy,” the canon and feudal laws, and the “aristocratic feud” (p. 31). Christendom was undermined by the decay of papal authority, the “military revolution,” and the Protestant Reformation. After a long period of disruptive anarchy, there emerged a new system of sovereign states oriented toward “popular eudemonism” (p. 264). A similar story can be told about Phillips's second case, “the Sinosphere,” which collapsed during the early twentieth century as a result of internal weakness, mechanized warfare, and cultural challenges from Japan and the West. Eventually, China transformed itself into a nation-state and entered into the sovereign system. Such transformations, Phillips argues, do not fit models of “hegemonic cycles” or “linear” evolution, and are better conceived of as “punctuated equilibria.”

War, Religion and Empire has the typical virtues and vices of all mediatory and synthetic works. Its theoretical framework is capacious and supple, and seeks to bridge the antinomies, not only between constructivists and realists but, more broadly, between culturalists and rationalists. “Soft” and “hard” power are each given their proper due. But partisans of parsimony and punchiness will be disappointed by this prolix and sometimes elusive book, which proliferates typologies and generally eschews strong adjudications. The argument is not easily summarized.

So far as the European materials are concerned—I cannot judge his handling of China—Phillips's judgment is generally surefooted. But there are a few slipups here and there, where the seemingly solid ground of historical “fact” has been destabilized by revisionist historians. For example, Phillips sometimes relies on outdated work positing an early modern “military revolution” (e.g., Richard Bean, “War and the Birth of the Nation State,” Journal of Economic History 33 [March 1973]: 203–221), and overdrawn claims about its impact on European state formation, advanced by Charles Tilly (see Charles Tilly, Coercion, Capital, and European States AD 990–1990; 1990) and others (for a critical review, see Philip S. Gorski, The Protestant Ethic Revisited, 2011). Similarly, after rightly emphasizing the persistently “composite” character of premodern states, Phillips inexplicably reaches for the old saw about an “Age of Absolutism,” which makes Jean Bodin's version of France the measure of all things. But these are small stumbles from which he can easily recover. Unlike Tilly, Phillips does not need the military revolution to begin in the year 1500; indeed, he tacitly acknowledges that the technological and tactical innovations in question began much earlier. Nor does the persistence of mixed government and divided sovereignty endanger the argument, because Phillips does not portray the Peace of Westphalia as an epochal turning point to the degree that many other scholars do, including Daniel Philpott. More vulnerable, perhaps, is Phillips's claim that the transformations of international orders are rapid transitions that resemble “punctuated equilibria.” By his periodization, for instance, the heyday of Latin Christendom stretches from 1100 to 1350. Its collapse, meanwhile, begins in 1350, while the emergence of the sovereign states system is still far from complete even in 1648. Perhaps we should speak of punctuated disequilibria?

In the concluding chapters of the book, Phillips reflects on the possibility that the current era of globalized terrorism might represent a threat to the sovereign state system, insofar as it has prompted preemptive and interventionist military strikes by the United States and may continue to do so in the future. Peculiarly, however, he says almost nothing about World Wars I and II. But were not these two conflicts a sort of globalized Thirty Years' War, a massive war of political religions, as it were? If one is searching for epochal turning points marking the emergence of new international orders, is not 1948 at least as good a candidate as 1648? Indeed, could one not argue that the apotheosis of 1648 was itself a sort of creation myth for this new order? Let us not forget that 1948 was also the year when Leo Gross originally opined that the Peace of Westphalia was the “majestic portal” to political modernity.

On the other hand, should we, rather, see it as the beginning of the end, as the moment when a global resurgence of religion began to undermine the secularized system of state sovereignty, as God's Century might suggest? But that perhaps is the subject for another book—or two.