Do we come to belief in God through personal encounter, or arguments, or both? When we ask ourselves ‘Why do we believe in God?’ our faith provides the first response,” offered St. John Paul II during a 1985 General Audience. “We believe in God because God has made himself known to us as the supreme Being, the great ‘Existent.’”

We believe in the unseen Trinity first and foremost because we have been convicted by grace through faith. “Faith comes from what is heard, and what is heard comes through the word of Christ,” affirms St. Paul (Rom. 10:17). Faith comes by the authority and testimony of another; and as recipients of God’s Word—which may come to us orally, in writing, or indeed through a direct encounter with the incarnate Logos, Jesus Christ—we can come to know truths that transcend the humble faculties of reason alone. We believe principally because we trust in what—or who—we have heard and encountered.

But if faith comes to us principally through the authority of another, does reason have a part to play in the acquisition of faith? According to St. Paul the answer is yes. For him it is not only God but that which God has created that can be revelatory. For as the Apostle says in his Letter to the Romans, the physical world can testify and reveal God’s “eternal power and divine nature, invisible though they are” (Rom. 1:20).

St. Paul placed great value on the revelatory capabilities of the senses. He believed that through philosophical contemplation that followed upon sense experience, we could come to know the existence of the divine Creator (Rom. 1:20). For St. Paul the senses could indeed reveal to us the real; indeed, by way of the proximately real the senses had the capability of leading us to the really real—the one God who simply and infinitely is.

But St. Paul knew that God might also reveal himself directly, through a person-to-person encounter, by the power of the Holy Spirit: “When we cry, ‘Abba! Father!’ it is that very Spirit bearing witness with our spirit that we are children of God” (Rom. 8:15).

Sensing God

We might be moved to believe in God because we have directly experienced him, independently of rational argument. But now here’s a question pertaining the reasonableness of belief based on experience: Would such a religious experience alone, in the absence of other evidence, be adequate to justify religious belief?

From Sigmund Freud to Richard Dawkins, skeptics have often expressed intense discontent towards the justification of faith based on religious experience. This is understandable. We can be tempted to believe many false things if we base our conclusions on feelings alone. But in recent times, Christian philosophers like the (rightly) esteemed Alvin Plantinga—inspired by Calvin’s notion of the sensus divinitatis or “sense of the divine”—have argued that belief in God may be treated as a “properly basic” belief—that is, a fundamental belief that requires no further justification to be rationally held.

On this view, then, belief in God based solely on religious experience may be fully justified if the belief is, 1) true, and 2) undefeated by objections. In such a case then one could be fully justified in believing in God even if they do not have “positive” arguments supporting their belief. Their interior experience of God would be enough. 

Arguments and Belief

But now let’s return to our initial question: Why do we believe in God?

We have already noted that God may reveal himself to us directly through the power of the Holy Spirit. But unless God reveals himself in this way, which is entirely by grace, God’s existence is not immediately evident to us. As St. Thomas tells us, God is self-evident in himself but not self-evident to us. Thus, even the unbaptized know God—but in a “general and confused way.”

And this is where human reason comes in. Indeed, rational arguments have much to add to brute religious experience. First of all, arguments serve to clear the mental debris that prevents us from seeing God more clearly. Second of all, they serve to authenticate our religious experiences and perhaps reveal more to us about the divine person—or persons—we have encountered experientially. Thus, just as religious experience may authenticate in a deeper way what we already know by demonstration, so also may philosophical demonstration authenticate religious experience.

Even if Plantinga is correct that arguments are not necessary to warrant belief in God, it would not follow that arguments have no important part to play in the life of faith. For if belief in God can be warranted by authentic religious experience and we can prove with positive arguments that theism is true, then as William Lane Craig has pointed out, we are doubly warranted to believe in God: first by grace through faith—but also by reason.

In Humani Generis (1950), Pope Pius XII echoed St. Paul’s affirmation of the possibility of natural theology when he wrote, “Human reason by its own natural force and light can arrive at a true and certain knowledge of the one personal God, Who by His providence watches over and governs the world.”

There are many paths by which we may come to philosophical knowledge of God. Such knowledge always begins in wonder—and then diverges. “Instinctively, when we witness certain happenings, we ask ourselves what caused them,” wrote St. John Paul II. “How can we not but ask the same question in regard to the sum total of beings and phenomena which we discover in the world?”

That the world exists unnecessarily—that is to say, that there is something rather nothing—is a fact that has incessantly poked at the minds of the deepest of thinkers. “Not how the world is, is the mystical, but that it is,” mused Ludwig Wittgenstein in his Tractatus. From St. Thomas Aquinas to G.W. Leibniz, great thinkers through the ages have concluded that that the world exists, despite not having to, points to a deeper metaphysical truth—a necessary being that explains all that is. Indeed, for St. Thomas it was not a necessary being but only (and necessarily) Being itself which could sufficiently explain the universe, who possessed all perfections—love, intelligence, creativity, and the like—without limit.

Many Ways to God

The ways to God by reason are many, and rarely work on the mind in isolation from the others. As St. John Henry Newman reminded us in his Essay in Aid of a Grammar of Assent, all of our reasons for belief converge upon one single subject from a variety of angles in a symphony of “converging evidences.” Echoing this insight, St. John Paul II observed:

A myriad of indications impels man, who tries to understand the universe in which he lives, to direct his gaze toward his Creator. The proofs for the existence of God are many and convergent. They contribute to show that faith does not humble human intelligence, but stimulates it to reflection and permits it to understand better all the “whys” posed by the observation of reality.

Indeed, the order, intelligibility, and “finality” (or goal-directedness) of nature also compel the mind, intuitively and discursively, to ponder the Supreme Intellect behind it all. Pope John Paul acknowledged the evidential power of such features of the natural world:

The evolution of living beings, of which science seeks to determine the stages and to discern the mechanism, presents an internal finality which arouses admiration. This finality which directs beings in a direction for which they are not responsible or in charge, obliges one to suppose a Mind which is its inventor, its creator.

Of course—as John Paul carefully notes in the passage above—it is the physical sciences that are best appropriated to investigate the phenomena of nature. But science does not precede nor supersede philosophical contemplation. Rather, science presupposes the philosophical, and at the same time integrates it into its method necessarily when it moves into the process of analysis.

For many, a study of metaphysics—that is, what is beyond (meta) the physical—has fallen out of style and into the shadow of the physical sciences. As particle physicist and theologian John Polkinghorne has observed, “Metaphysics is not a word that many scientists feel happy with. It is not uncommon for the concept to be dismissed.” But, he counters, this dismissal is in vain. “In actual fact,” says Polkinghorne, “it is impossible to think seriously without taking a metaphysical stance, since this simply means adopting a world-view. We think metaphysics as naturally and inevitably as we speak prose” (emphasis added).

Indeed, we do. Granted, our metaphysical thinking is not always concretely discursive; that is to say, we are not always aware of our assumptions, premises, and ways of getting to our conclusions, nor are we always thinking in—or even able to think in—the technical jargon of philosophy. That being said, by the virtue of the fact that we are rational, we are ever in the state of mentally peeling back the layers of reality, always drawing conclusions and making distinctions about what is and what ought to be. That being said, we are not often explicitly cognizant of our mental activities as metaphysical. “All men have a reason,” wrote St. John Henry Newman,” but not every man can give a reason.”

When it comes to the existence of God, then, we cannot help but seek understanding to supplement and fortify our faith. God has created us for himself; and as art reveals something of the artist, so also does the world he has placed us in reveal the nature and divinity of God. Every person by nature desires to know, wrote Aristotle famously. And we might also add that every person—at least in a general and confused way—desires to know God. Our rational nature permits us as human persons to intuit God experientially, but also all-at-once instills within us an irremediable appetite to know God intellectually. Thus, both experience and argument play pivotal roles for belief in God.

Believing in God

Why do we believe in God? We believe in God, first, by faith. Trusting in the authority of the Church, strengthened by the wisdom and witness of the Sacred Scriptures, inspired by the testimony of the saints, and moved interiorly by the Holy Spirit, we believe by grace that God has revealed himself to us.

But we believe also because our minds tell us that God is real and Christianity is true. We believe what we know, we know what we believe, and the coming together of faith and knowledge happens not by force but by a harmonious integration. As grace perfects nature, so faith perfects reason. Or in the words of Pope Benedict XVI: “Faith presupposes reason and perfects it, and reason, enlightened by faith, finds the strength to rise to knowledge of God and spiritual realities.”