This is an incredibly learned book by an author who has been publishing on the philosophy and sociology of religion for years, as is evident from the numerous essays he has contributed to many journals across different languages. It is without question one of the most comprehensive, synoptic, insightful, and balanced overviews in the recent flurry of books dealing with religion, Christianity, secularization, secularism, secularity, and thus implicitly with modernity, modernization, and progress.

The book begins with an overview of the Blumenberg/Löwith debate that was launched in 1962 when Blumenberg wrote for a meeting of the Allgemeine Gesellschaft für Philosophie in Deutschland what would eventually become his important book The Legitimacy of The Modern Age. This book appeared in various versions throughout the sixties and seventies, growing with each new edition. The theme of the 1962 conference was “Philosophy and the Question About Progress.” The table of contents of the proceedings is a stellar who's-who in German philosophy: Adorno, Blumenberg, Habermas, Löwith, and others. Blumenberg's essay in that volume was titled “‘Secularization’: Critique of a Category of Historical Illegitimacy,” now available in translation in the recent History, Metaphors, Fables: A Hans Blumenberg Reader (Cornell University Press, 2020). The subtitle is very telling, especially in the context of the conference's theme: What does philosophy have to say about progress? What is progress, and can we speak of philosophical progress? I will return to this point later.

Costa then discusses the important work of sociologist David Martin in Chapter 2. This chapter was particularly helpful in recovering for readers seminal books that Martin wrote that have been forgotten or neglected. Chapter 3 comprises a careful discussion of Charles Taylor's A Secular Age (2007), while Chapter 4 explores Hans Joas’ books on religion, human rights, and human dignity. The title of Chapter 5, discoursing on “The Postcolonial Point of View,” does not carry the name of an author. It is dedicated to Talal Asad, the Saudi- born anthropologist now teaching in the U.S. There follows a chapter on Marchel Gauchet's important books on religion and the “disenchantment of the world,” and a balanced but critical chapter on Jürgen Habermas's work on what he called “faith and knowledge.” The last substantive chapter looks at the long “shadow” that Nietzsche has projected in our age; in this chapter, Costa treats Gianni Vattimo and Peter Sloterdijk.

This is a book that should be on the desk of anyone who is interested in the debate about “secularization,” and its most recent incarnations. When approaching a text this rich, and the product of years of research and writing, one hesitates to raise issues. Yet, the role of the reviewer is to point to alternative readings and missed detours. I think a couple can be pointed out, without diminishing the worth of the book. First, the book is perhaps too abstemious and humble in its theoretical aims. We move from author to author, with sometimes the note that this is a philosopher, a sociologists, an intellectual historian, a Nietzschean-Heideggerian postmodernist, etc. The question pending is, what do different disciplines bring to the table in this debate? Martin is a sociologist and thus his approach is different from that of Taylor, or Talal Asad's, who is by training an anthropologist. Blumenberg, on the other hand, is such a sui generis thinker one hesitates to call him an intellectual historian, although he did work in this area. He is probably best known for two ideas: metaphorology and non-conceptuality, which are directly relevant to his critique of what Costa calls the “secularization theorem.”

The chapter on Habermas, while very informative, could have benefited from a disaggregation of the different ways Habermas has dealt with Christianity and religion in general. Habermas's recent two-volume work titled Also a History of Philosophy (2019), will force us to rethink a lot of what he has been arguing over the last two decades. Over his long intellectual itinerary, Habermas has dealt with Athens, Jerusalem, and Rome, metonyms for different relations to religions, from different disciplinary standpoints: philosophy, politics, sociology, and what he calls reconstructive narratives.

All of these thinkers have different methodological commitments. This means we must also ask: Does a quasi-Hegelian story about secularization, as one may find in Taylor and to some extent also in Habermas, contribute something different from a genealogical and/or anthropological account, such as we might find in Asad, Sloterdijk, and Joas? Costa tells us in the book's Introduction that his work is a “meta-discourse,” i.e. a discourse about the discourses dealing with the myth of secularization. To this extent, we could have been offered a meta-map of the discourses about discourses on what I would call the thesis that “we have never been secular,” or “we have not been secular enough.”

It is difficult to appreciate Costa's polemic against Löwith without taking into account Blumenberg's two other doorstoppers, Work on Myth and the Genesis of the Copernican World, which show how secularization is not the illegitimate expropriation of key ideas from the Judeo-Christian worldview. The Nietzsche chapter, rightly, focused on his (in)famous pronouncement that “God is dead,” and we, humans, have killed him. But it missed the opportunity to discuss Nietzsche's third essay in his On the Genealogy of Morality, in which he claims that we could not have become the creatures we have become without the burden of conscience, the burden of our guilt for having sinned against a distant and cruel God.

I want to close by returning to Blumenberg's 1962 essay, written for a congress of philosophy with the theme of progress. The inchoate question is whether secularization is integral to progress, or whether progress is a religious fetish that deludes us. When we ask whether we are secular, and if so, to what degree, we are also asking: are we progressing; are we modern, are we children of our own time, not beholden to a God we exiled from our lives? Is modernity and modernization, and progress thereby, a zero-sum game in which religion loses and the secular wins? And, of course, implicit in these questions is the question after the progress of religion itself. If philosophy admits of progress, why not accept that religions as well progress? But with this last question, we turn to a different set of interlocutors: Arens, Barth, Bonhoeffer, Küng, Metz, Rahner, Sölle, and many others, who have been asking about secularization and the progress of religion and theology from the other side of the aisle, so to say. This wonderful book raises these and many more questions.