Surely one of the greatest concerns of the papacy of Benedict XVI was his ongoing attempt to overcome the dualism between faith and reason—and hence, between faith and life—that dominates Western culture at present, even among those of us who are Christian. Dualism inclines us to think that faith is something that belongs to the realm of the things we "do," perhaps with our activities on a Sunday or in carving out a portion of our day for Christ, as though He were something we make happen, as though He didn't have everything to do with life, as though He were not "all, and in all" [Col. 3:11].

In his encyclical letters on love and hope, and in the key addresses he gave, including ones at Regensburg, La Sapienza and the Bundestag, Benedict everywhere insisted that the greatest challenge facing the Church today is her need to overcome this dualism at the heart of modernity and "to devise effective ways of proclaiming to contemporary culture the 'realism' of her faith in the saving work of Christ."

Now the encyclical on faith, Lumen Fidei, itself effectively proclaims "the realism of faith" and sheds light on why we may well indeed see the fruitful proclamation of this truth as the Church's greatest challenge at this historical juncture. Lumen Fidei is, in many respects, a masterful consummation of Benedict's thinking on this question; and, though Benedict and Francis may well have made distinctive contributions to the encyclical, they are clearly united in their desire to convey, above all, the preeminent Christian truth that the Logos is the self-communication of God's Presence in all of reality—a Presence that can be truly known and verified in experience, in our "concrete life-stories," as Francis calls them in Lumen Fidei.

"Our culture has lost its sense of God's tangible presence and activity in our world. We think that God is to be found in the beyond, on another level of reality, far removed from our everyday relationships. But if this were the case, if God could not act in the world, His love would not be truly powerful, truly real, and thus not even true, a love capable of delivering the bliss that it promises. It would make no difference at all whether we believed in Him or not."

How did this situation come to pass where the tangible presence of God has become increasingly lost in our culture and where "visible and material realities are" no longer "seen to point beyond themselves to the mystery of the eternal"? This is no mere academic question, for when God becomes so far removed from reality that we think of ourselves as incapable of knowing Him in any way through what is real, faith is thereby considered to be irrelevant to life's needs, and we soon have no need of faith. The evidence of this is everywhere around us, so much so that today even a great many Christians live what is in effect a practical atheism.

A significant contributing factor to this state of affairs was the self-limitation of reason imposed by modernity, a limitation that was radicalized by the impact of the natural sciences and that reduces the real to only what can be empirically verified or deduced mathematically. It doesn't strain credulity too much to see how this reduced understanding of reason has as a consequence a steady refusal of belief in God. In comparison with what is empirically verifiable, the question of God seems unreal, and can be readily dispensed with as we go about our affairs in the world.

Or, as an alternative response to reason's seeming incapacity, faith becomes for many Christians, as Francis points out in Lumen Fidei, with a nod to Kierkegaard and his ilk, an irrational "leap" into the darkness, a work of the individual subject that can have no claims on our life in common.

There are serious consequences to the position that relegates faith to the realm of the irrational, and we are already seeing the loss of confidence in truth and the extreme skepticism that inevitably follows, as Francis notes in his first encyclical.

"We are willing to allow for subjective truths of the individual, which consist in fidelity to his or her deepest convictions, yet these are truths valid only for that individual and not capable of being proposed to others in an effort to serve the common good."

To respond to this challenge, Lumen Fidei invites us, as Benedict did at Regensburg, to once again "broaden reason" and to resist the reduction of reason imposed by modernity. The broadening of reason is imperative, we discover, because any attempt to reduce reason's scope necessarily results in the attenuation of faith.

But what does it mean, precisely, to broaden reason?

It perhaps comes as no surprise that the current pope and his predecessor should call for a broadening of reason. After all, the Catholic tradition's defence of the idea that "grace perfects nature and reason, it does not destroy them" is there in seminal form in the earliest Christian generations and down through the centuries. Tertullian's famous quip, "What indeed has Athens to do with Jerusalem?... Away with all attempts to produce a mottled Christianity of Stoic, Platonic and dialectic composition! With our faith, we desire no further belief," was never more than an extreme minority position. The Fathers of the Church and theologians of the Middle Ages, in their consideration of the manner in which natural theology ought to be understood in relation to Biblical revelation, or in which human philosophizing ought to be understood in relation to religious belief, definitively rejected the dualism implied in Tertullian's view and defended the idea that Athens had everything to do with Jerusalem. In fact, providence had so ordained history that Athens and Jerusalem—and Rome as well—had prepared the way for the birth of Christianity (cf. Augustine's City of God). Saint Clement of Alexandria even went so far as to argue that Greek philosophy had been given to humankind as a second source of Divine truth, akin to Holy Writ itself. Echoing these voices in the Tradition, Benedict stated at Regensburg, "The encounter between the Biblical message and Greek thought did not happen by chance."

However, debates concerning the Hellenization of Christianity that occupied the earliest Christian generations, or the program of de-Hellenization that has marked the landscape of modernity, are not Lumen Fidei's principal concern (although the document does remark on the contribution the Greek metaphysical heritage made to the Christian faith). More fundamentally, the encyclical, in calling us to broaden reason, proposes that faith itself is a form of knowledge of reality that best coincides with our rational nature—a kind of knowledge that gives us "new eyes to see" more truly the meaning of things.

To further understand the significance of this point about faith, it is worth referring to the well-known chapter and verse from the Letter to the Hebrews that provides something of a definition of faith. Interestingly, while Lumen Fidei refers a number of times to the Letter, it nowhere refers to Heb. 11:1. Benedict's discussion of the Letter in Spe Salvi, however, provides an important background to the discussion of the nature of faith in the current document. In Spe Salvi, Benedict examines the exegetical controversy that arose in the wake of the Reformation concerning the definition of faith given in the 11th chapter of the Letter. The relevant verse is: "Faith is the hypostasis of things hoped for; the proof of things not seen." The Fathers of the Church and theologians of the Middle Ages consistently rendered the Greek word hypostasis in Latin as the term substantia, so that the verse reads, "Faith is the 'substance' of things hoped for; the proof of things not seen." Luther departed from this reading when he took hypostasis (substance) not in the objective sense of a reality present within us, but in the subjective sense, as an expression of an interior attitude and disposition of the subject. On his reading, the rendering of the passage becomes "Faith is standing firm in what one hopes, being convinced of what one does not see." But as Benedict remarked in Spe Salvi that the Greek term elenchos "does not have the subjective sense of 'conviction' but the objective sense of 'proof.'"… And the concept of "substance" implies that through faith—albeit in a tentative way—"there are already present in us [and in what is real] the things that are hoped for."

"Faith is not merely a personal reaching out towards things to come that are still totally absent: it gives us something. It gives us even now something of the reality we are waiting for, and this present reality constitutes for us a 'proof' of the things that are still unseen."

How so? What, in other words, is the road that reason takes in order to admit faith, so that faith can become this way of seeing present reality at a deeper level, so that it can become a "luminous vision of existence"? In Fides et Ratio, John Paul II describes the process thus:

"…when the why of things is explored in full harmony with the search for the ultimate answer, then human reason reaches its zenith and opens to the religious impulse [that represents] the highest expression of the human person, because it is the highpoint of his rational nature."

When reason expresses itself as openness to Being, then religiosity is the discovery made in that openness. Looking at our experience with integrity, we discover that every thing in reality, every event, solicits us, and is an invitation to, or a sign of, something more. We discover that we are made for the Infinite, that we have, to paraphrase Saint Augustine, been made for God and have a heart that is restlessly seeking Him. It is a persistent factor of our experience to intuit in reality this something more; not to admit it—to deny the evidence of our lived experience—is therefore unreasonable.

For Lumen Fidei, recognition of this apex, this docta ignorantia, or "known unknown," is what is most adequate to reason. Contrarily, a reason that rests at the appearance of things, with its own analyses and interpretations, refuses the initiative that the Mystery, which is God, takes in history, and in the story of each of our lives, inscribed as He is in our hearts.

But, of course, it is one thing to claim that humans are naturally religious, and quite another to suggest that faith itself is in any way something we can reach or generate on our own. Structurally we are made for God, and what best coincides with our rational nature is this awareness; but faith is an utterly gratuitous gift of God, which doesn't happen because we speak of Him, discourse about Him. It happens because He makes it happen! "God cannot be reduced to an object" of our interpretations and analyses. "He is a subject who makes himself known and perceived in an interpersonal relationship," Francis writes in Lumen Fidei. "Faith is born of an encounter which takes place in history and lights up our journey through time."

Against all forms of Gnosticism that begin with the human rather than the Divine initiative, Lumen Fidei everywhere insists that "rather than ourselves possessing truth, it is truth that embraces and possesses us."

So how do we bridge the gap, then, between the seemingly disparate ideas that faith is a gratuitous gift of God, that He takes the initiative to enable us to know Him, and by the same token to suggest that we are naturally religious (i.e. made for God), that "God is light and He can be found also by those who seek Him with a sincere heart," as Francis writes? For if God's gift is utterly gratuitous, it would seem that it matters little whether or not our nature is hard-wired for Him or our heart restlessly seeks Him.

The resolution of this seeming contradiction is simple: precisely because our heart is made for God, when He comes to meet us, we know that He is what we have been truly looking for. He is what truly corresponds to the deepest needs of our heart, according to Luigi Giussani in The Religious Sense. It remains for our freedom to respond to the Divine initiative or—dramatically—to refuse it.

Yet we are not alone in this journey of faith; we are truly helped in our journey in a concrete way by our fellow travellers. Francis wrote in Lumen Fidei, in a passage worth quoting at length:

"It is through an unbroken chain of witnesses that we come to see the face of Jesus. But how is this possible? How can we be certain, after all these centuries, that we have encountered the 'real Jesus'? Were we merely isolated individuals, were our starting point simply our own individual ego seeking in itself the basis of absolutely sure knowledge, a certainty of this sort would be impossible. I cannot possibly verify for myself something that happened so long ago. But this is not the only way we attain knowledge. Persons always live in relationship. We come from others, we belong to others, and our lives are enlarged by our encounter with others. Even our own knowledge and self-awareness are relational; they are linked to others who have gone before us: in the first place, our parents, who gave us our life and our name…."

And so, "the individual's act of faith finds its place within a community, within the common 'we' of the people who, in faith, are like a single person—'my first-born son,' as God would describe all of Israel [cf. Ex. 4:22]. Here mediation is not an obstacle, but an opening: Through our encounter with others, our gaze rises to a truth greater than ourselves."

Just as faith is a gratuitous gift that best corresponds to our rational nature, and hence fulfills rather than bypasses our humanity, similarly, faith in Christ comes through what is real—namely, a concrete companionship of people who comprise the Church for us and who help our faith become a knowledge that is certain.

There is much more that could be said about this extraordinary document. What is most striking, perhaps, is that, in inviting us to recover a sacramental view of reality, Lumen Fidei provides us with an orientation towards existence that is our best hope for overcoming the dualism between faith and life that characterizes our world.