In 1950, Pius XII issued the encyclical Humani Generis as a response to existentialism, which he considered a mortal threat to the Church. According to the Pope, existentialism was an “erroneous” doctrine that offered an irrational metaphysics in the place of true religious order. Though he is not mentioned in the encyclical, it is clear that Pius was thinking of French philosopher Jean-Paul Sartre, who had shot to global fame after the end of World War II and whose complete works had been added to the Vatican’s Index of Prohibited Books two years earlier. In 1956, The Second Sex, the most prominent work of another great existentialist, Simone de Beauvoir, was accorded the same honor. Sartre and de Beauvoir’s ideas followed from the existential reimagining of phenomenology, which had become one of the most important and influential philosophies in Europe over the course of the first half of the twentieth century. By attending to our situated human experience, they thought, phenomenology demonstrated human finitude, how our experience of the world was always limited and partial, and as such undercut religious claims that had often required appeals to an absolute. As Sartre and de Beauvoir’s friend and collaborator Maurice Merleau-Ponty put it in 1951, commenting on the encyclical, Catholicism required the embrace of “ontology in the classical sense of the word.” But this embrace, he argued, was “the negation of phenomenology.”

Nevertheless, at precisely the moment Pius XII was developing his attack on the existential inheritors of phenomenology, a later occupant of the Throne of St. Peter was throwing himself into phenomenological research. In 1953, the future John Paul II, Karol Wojtyła, would finish his thesis on phenomenology, drawing on the work of Max Scheler in order to provide a close analysis of the experiential aspects of ethics. This analysis, he considered, could provide an important supplement to the insights of Catholic metaphysics. In fact, despite its common association with unbelief, the history of phenomenology can boast a large cast of religious actors, not least the future saint Edith Stein, who was first an assistant to the founder of phenomenology, Edmund Husserl, before becoming a Carmelite nun, and who was murdered at Auschwitz in 1942. Later, religious thinkers would engineer what came in the 1990s to be known as the “theological turn” in phenomenology, in which philosophers like Jean-Luc Marion, Michel Henry, and others marshalled its subtle analysis of the structures of human experience to examine religious phenomena. Some went so far as to suggest that phenomenology was inherently religious, perhaps even a form of Christianity. The judgment has been seconded by prominent critics of the movement. The French speculative realist Quentin Meillassoux has argued that phenomenology has been one of the most powerful intellectual forces legitimizing religion in the modern world. And though one might be tempted to see this division as that between phenomenology’s pious beginnings and its unbelieving existential heir, neither had a clear or univocal relationship to religious practice and belief. Indeed, if anything, one might expect existentialism to be more open to religion, drawing as it did on the work of Søren Kierkegaard and developed in the twentieth century by a range of Catholic, Protestant, and Jewish thinkers, amongst others.

Religious and secular thinkers tend to speak different languages and, too often, talk past each other. Even attempts at reconciliation raise the suspicion that they shelter values and presuppositions that tilt the playing field from the start. Jürgen Habermas’s account of the “post-secular” is a case in point. That is why the curious relationship between phenomenology and religion is so fascinating. Phenomenology does not pretend to be a neutral space where those who believe and those who do not can thrash out their differences. Rather it presents a strange paradox, a form of thought that has been variously claimed as the basis of a resolute atheism and as the most philosophically rigorous account of religious faith. Here, there are those on both sides who can claim to be on home ground. It thus provides a privileged perspective for re-examining the relationship between the religious and the secular.

Phenomenology attends above all to the givens of experience, and looks with fresh eyes on how we grasp the world. For Husserl and the many phenomenologists who followed his lead, this meant that we should put aside the presuppositions of a naturalist worldview, especially as transmitted by the sciences. Since scientific naturalism had been so central to nineteenth-century attempts to sideline religious belief, to exclude purported experiences of the sacred, the divine, or God from respectable intellectual discussion, phenomenology seemed to be a valuable ally for religious thinkers trying to open a space for faith in modernity.Many homed in on the phenomenological conception of transcendence. For Husserl the object of our experience gave itself as transcendent. Taking the example of perception, Husserl pointed out that a spatial object never gives itself to us in all its aspects in one go. It is always more than we can grasp. Despite the difference between this transcendence and the putative transcendence of God, many thought that the former opened the door to understanding the latter. Indeed, later figures suggested that religious revelation might be paradigmatic for experience in general. In all these cases, phenomenology seemed to level the playing field and open up the possibility for a rigorous attention to the object of religious faith. The political theorist Leo Strauss recalled Husserl declaring, “if there is a datum ‘God,’ we shall describe it.”

In addition, phenomenology is replete with concepts and ideas whose roots can be traced to religious traditions. Husserl developed his pivotal conception of intentionality, that consciousness is always consciousness of something, in engagement with the work of the ex-Priest Franz Brentano, who had himself drawn it from medieval scholasticism. Husserl’s student Martin Heidegger, who had been trained in Catholic theology, developed his existential rereading of Husserl’s phenomenology in the 1920s while studying St. Paul, St. Augustine, the medieval mystics, and Martin Luther. The multiple historical and potential connections between phenomenological and religious ideas help explain the curious rash of conversions that dot the early history of the movement, from Adolf Reinach’s embrace of Protestantism shortly before his death on a World War I battlefield, to Edith Stein’s conversion to Catholicism five years later in a Rhenish orchard.

And yet, in his published works at least, Husserl dedicated very little attention to explicitly religious questions. In his 1913 book Ideas, he suggested that the dogmatic content of theology and the transcendence of God would both be victim of the phenomenological reduction, placed in brackets along with the presuppositions of naturalism in any rigorous analysis of experience. It is for a similar set of reasons that Dominique Janicaud denounced the so-called “theological turn” in phenomenology as an erroneous detour. The moment philosophers moved beyond examining the “intertwining” of the invisible and visible to confront the fully transcendent was the moment they left phenomenology behind.

A similar opposition structures Heidegger’s thought. In his 1927 lecture “Phenomenology and Theology,” Heidegger distinguished between theology, as the regional science of faith, and phenomenology, which uncovers the structures of being. The latter could ground and delimit the former, but was necessarily independent of it. According to this argument, faith was the “mortal enemy” of philosophy. As he had argued at the beginning of the decade, philosophy had to be “in principle a-theistic.” Thus, despite the tempting parallels between his account of human existence and that of many religious thinkers, Heidegger was adamant about their differences. In a 1951 interview, Heidegger posed the distinction in even starker terms: “if I were to write a theology—and sometimes the thought tempts me—the term ‘being’ would not appear in it.” For all their differences, then, Husserl and Heidegger maintained what they saw as the neutrality of phenomenology. Phenomenology would examine without prejudice, especially any prejudices handed down by religious tradition. Even at the most open to religious belief, Husserl doubled down on this neutrality, describing phenomenology as a “non-confessional path to God.”

Despite these ecumenical aspirations, what is fascinating about the history of phenomenology is that the politics of religious difference is rarely far away. Phenomenology has been invoked to promote a number of different religious stances: Jewish, Islamic, and, within Christianity, Protestant, Orthodox, and Catholic, amongst others. In fact, a close examination of the history of phenomenology helps disintegrate the category of “religion,” not only distinguishing its multiple strands, but also showing the forces that bring them together and tear them apart. It is telling that in his most famous work, God Without Being, the Catholic philosopher Jean-Luc Marion should have introduced his religiously inflected phenomenology with an attack on Thomist ontology—what for much of the past thousand years has counted as the canonical Catholic philosophy. Marion’s hostility is more curious still when one considers that Thomists, like Wojtyła and the rescuer of the Husserl Archives, Herman Leo Van Breda, were some of the first religious thinkers to engage with phenomenological ideas. Not for nothing did Edith Stein in the early days of the movement recall how Husserl’s phenomenology gave the impression of being a “new scholasticism.”

The strange and often contradictory ways that phenomenology has been woven into and through diverse religious traditions are the subject of this forum. Illuminating the central tension, Dermot Moran paints a rich picture of Edith Stein, who reoriented the work of Husserl and Heidegger for distinctly theological purposes. He shows how Stein used the phenomenological method to reveal not only human finitude (and thus for Heidegger, atheism), but also a deeper eternal core and an experience of God as that of overwhelming plenitude. The next two essays raise questions about this religious reorientation by examining neighboring intellectual developments. In her reading of the “American phenomenology” of William James, Amy Hollywood shows how the attention to religious experience, even at its most intimate, depends upon interpersonal relations and, by extension, institutional belonging. She thus asks how much a phenomenology of religious experience is able to (and indeed how much it should) sideline history and theology. Noreen Khawaja makes a similar argument by relating Husserl’s phenomenology, through Husserl’s erstwhile colleague and interlocutor, Rudolf Otto, to the work of Swedish artist Hilma af Klint. She shows how af Klint’s abstraction, which parallels the phenomenological reduction, also relates to her practice as a medium in the context of spiritualism in turn-of-the-century Stockholm. Abstraction thus authorized, not bracketed, particular spiritual practices and claims. The final essay redirects this line of thinking back to the heart of the phenomenological movement. Francois-David Sebbah examines a 1986 debate between Jean-Luc Marion and Jean-François Lyotard over the meaning of Emmanuel Levinas’s work. They provided opposing interpretations of and indeed corrections to Levinas’s phenomenology of the Other, which would mark it as “Christian” or “Jewish” respectively. As Sebbah concludes, even when bracketing doctrinal considerations, phenomenology might be guided by “orientations in existence” that are never truly free from religious influence.

In Pius XII’s 1950 encyclical, he did not concern himself immediately with the atheistic existentialists. Rather he aimed his words first and foremost at those Catholics who “desirous of novelty” had sought to express the Church’s doctrine in the “concepts of modern philosophy,” including existentialism. As such, he worried that they withdrew “themselves from the sacred Teaching Authority and are accordingly in danger of gradually departing from revealed truth and of drawing others along with them into error.” The problem for the Pope was therefore not a philosophy that attacked the citadels of religion from the secular outside, but rather one that Catholic thinkers embraced as supportive for their faith, and thus one that was already at work within the Church. In phenomenology, the lines between the religious and the secular are never clearly and decisively drawn. And that indeterminacy, rather than any simple association with unbelief, is what made it so troubling.

Note: The essays in this forum derive from a workshop held at Harvard University in October 2019, which was co-organized by Peter E. Gordon and Edward Baring, and was sponsored by the Harvard Colloquium for Intellectual History and the Minda de Gunzburg Center for European Studies, with the support of the The Cultural Services of the French Embassy of the United States.