A Philosophical Case for Christianity

Here, I think, is a way philosophy can point to Christianity.

Here, I think, is a way philosophy can point to Christianity. (By philosophy, I don’t mean anything technical; I just mean thinking deeply about common experiences, seeking out their necessary causes or conditions, and trying to set things in relation to a whole, which is to say, to form some Big Picture.) It requires accepting a classical perspective—which, in my view, is a good thing—by giving old-fashioned answers to questions about the nature of goodness, the human person, or why there are things that exist which don’t have to exist.¹ This account might sound a little strange at first, maybe even a bit spooky, but I believe it makes a lot of sense. In fact, I think it is true. So, let me outline the basic components and show how, in my opinion, they point toward something like Christianity. (Note: I won’t be defending all these classical ideas here, including the existence of God—I’ve done that elsewhere—just reporting them and showing how they connect with Christianity.)

But first, what do I mean by "point"? Certainly, I don’t mean "prove." Rather, I mean something more along the lines of indicating, confirming (to some degree), providing a clue for, etc. In other words, I might have titled this post How Philosophy Can Lead to Christianity, mirroring the book How Reason Can Lead to God by my friend Joshua Rasmussen, in which he shows how it can be reasonable to believe in God based entirely on philosophical considerations—he doesn’t claim that it’s unreasonable to disbelieve in God, as far as I know. In a similar fashion, that’s all I hope to accomplish here. I admit this is a fairly easy project because I think reasonableness (that is, minimally, where someone isn’t violating any obvious epistemic norms) comes relatively cheaply. Nevertheless, that doesn’t mean it’s without value, especially given how many people think religious belief is somehow unreasonable or unmotivated. And just because something is cheap doesn’t mean it’s free.

Next, what do I mean by Christianity? This is a bit harder to pin down. I’m Catholic—so that's where I’m coming from—but the case I’m about to make points more broadly to commitments like the Incarnation and Atonement (God becoming man so that humanity might be "at one" with God), which are beliefs shared by many Christians.² Of course, Christianity extends beyond these ideas for both Catholics and Protestants, but what I focus on below should, I hope, be enough to help Christians see some philosophical support for their beliefs—or for those who aren’t Christians to perhaps see that as well.

With that out of the way, let’s begin.

In the classical view, God exists. But God isn’t just some powerful demiurge-type being that gets the physical universe up and running and then lets it carry on under its own steam. Rather, God is the ultimate source and foundation of existence itself. Peculiar as it may seem, God just is existence itself—pure existence. In this classical view, people had a rather rich or "thick" conception of existence: they believed that existence is what gives something—and all its properties—real presence in the world. It’s the principle of actuality. Many of these thinkers also held that most things we experience are such that what they are—their essence—doesn’t guarantee their existence. These things are contingent beings, which could have possibly not existed, as they depend on something else to impart existence, or actuality, to them. Therefore, whatever is ultimate or foundational—since many traditional thinkers rejected the idea of infinite loops or regresses—must be something whose essence is nothing other than its existence. For classical theists, it makes sense to say that existence itself exists—and that this is God.

God, then, is seen as a being whose essence just is his existence—a being without any restricting or limiting principle that "contracts" being, so to speak, into some finite configuration, like a horse, a dolphin, or a molecule. The idea is that unbounded existence—existence itself, God—is the fullness of being, possessing only and every property of pure positivity, properties that do not inherently involve limits or bounds. These include, but are not limited to, attributes like power, knowledge, goodness, and love. (For example, curiosity wouldn’t apply, because curiosity implies a limitation in knowledge. The same goes for having a height, weight, or being any sort of material body³) On this view, if God is the only being who exists necessarily—because His nature is simply to exist—then God is the source of all the existence or actuality that everything else has throughout its existence.⁴ God doesn’t just set things in motion; He sustains them existentially. All things exist only insofar as God is actively upholding them. Thus, God is truly omnipresent, as a cause is to its effect, in everything within creation.

In the classical view, God is also perfectly good. This belief stems from the theory of the transcendentals, a traditional idea that holds being has different aspects. Under the aspect of intelligibility (in relation to intellect), being is truth; under the aspect of desirability or perfection (in relation to will), being is good. For classical theists, being is convertible with goodness, meaning that God, as fully actual and unbounded being, with no potentials to fulfill for the attainment of any further or higher perfection, is unbounded goodness or absolute perfection.

The next several paragraphs are highlighted for being slightly more technical (though hopefully helpful), but they are not essential to the overall aim of this article. Feel free to read if you're interested, or skip if you're not.

Essentially, I want to focus here on how goodness tracks being (or actuality) and ties into the idea of perfection. Grasping this idea will help us better understand why people have long believed God is perfectly good, and what that implies, if anything.

Take, for example, how we commonly speak of things as good or bad. We say a tree is good when it has certain features, like deep roots and vibrant leaves, and we say a knife is good when it has sharpness and durability. Importantly, following the philosopher Peter Geach, we recognize that "good" is used attributively in these cases.⁵ This means the meaning of "good" depends on the kind of thing being described—a good tree is good in a way specific to trees, and a good knife is good in a way specific to knives. The adjective "good" doesn’t have a standalone, universal meaning; it only makes sense in relation to the noun it qualifies. For instance, if someone says, "I’m holding a good one," you won’t know what they mean by "good" until you know what they’re referring to—whether it’s a knife, an apple, or something else.

Nevertheless, the attributive sense of "good" is clearly tied to the actuality or being of the thing: a good tree is a tree that fulfills its potential, possessing the relevant actuality of a healthy, flourishing tree. There is nothing over and above the being of whatever tree we call good that is its goodness; the goodness is simply the being that ought to be there, given the sort of thing a tree is. Similarly, a good knife is one that fully actualizes its nature by being sharp and durable. In these cases, goodness is about how well something achieves the fullness of its being (often, but not always, the notion is functional). Goodness, in this sense, tracks how much actuality a thing has, as is most relevant to its nature.⁶ This is thesis—another one of those old-fashioned ideas—is known as the convertibility of being and goodness.

As mentioned earlier, this understanding of goodness is crucial for grasping why and how we apply the term "good" to God. When we say God is perfectly good, we're not using "good" in exactly the same way we do for created things like trees or knives (univocally), though we're also not using it in a completely different way (equivocally). Rather, we're using it analogically, with similarity-in-difference.⁷ While God’s goodness is tied to His actuality, as it is with anything, God’s being—and by extension, His goodness—is radically different from that of creatures. For example, a tree or knife is good insofar as it actualizes its species-specific potential, but God is purely and fully actual, having no potential. Moreover, God’s goodness is not relative to any kind because God is not a member of any kind (like a tree or rabbit). Instead, God is the necessary condition—Being itself—from which all kinds exist, seen as finite imitations of God’s infinite fullness.

Also, remember that whether a feature can be positively attributed to God depends on whether it is purely positive—something that doesn’t inherently imply a limit or boundary, like curiosity or height would. This means that God’s perfection (which means to be complete or thoroughly made), as the fullness of being, is absolute, unlike the relative perfection that things of specific kinds possess. Finally, according to the theory of transcendentals (or the convertibility principle), God, as the fullness of being, is also the fullness of goodness. In Platonic terms, God simply is the Form of the Good. The ultimate existent is the ultimate good.

Now, God is perfectly good by metaphysical necessity, which raises the question: Why would God create? If God is perfect goodness, He doesn’t need anything to fulfill his nature—He’s already perfect. However, there are two ways to enjoy goodness. First, one can rest in it. Second, one can share it. This connects with another classical idea: namely, that goodness is self-communicative—that goodness naturally emanates and manifests itself through sharing.⁸ If this idea is right, then we have reason to think God would create, if only through an act of sheer gratuity. Perhaps God didn’t have to create; maybe there is some relational life within God that is intrinsically self-manifesting goodness (as in the Trinity⁹). Nevertheless, it seems fitting for God, as the supreme good, to create out of gratuity. It would be a good thing to do, and we might expect Goodness itself to do good things. That would be consistent with God’s unboundedly good nature.

But wait—I think we can say more. After all, it’s one thing for God to share the goodness of existence with us—and that’s amazing, since all other goods depend on the good of existence. But perhaps God would go further and share the greatest good with us, which is Himself—the supreme good. God might not only want us to exist, but to exist in union with Himself. To be in union with God requires being a certain kind of being: a conscious entity with intellect and will. A rock, while interesting, doesn’t seem capable of enjoying union with God because rocks aren’t persons.

This, I think, is where things get even more interesting. God is goodness itself, and it is good for God to create. Generally speaking (and I think this is obvious), it’s better to create more rather than less, which suggests that God would create abundantly, encompassing a wide range of beings—a Great Chain of Being, if you will—ranging from simple things like rocks to plant life, animal life, and rational life. In other words, God’s existence predicts or anticipates this expansive hierarchy of creation. But God doesn’t just want things to have the good of existence; He wants them to have the good of union with Himself. While rocks and plants may not achieve this independently, God could create a being that unites the entire spectrum of creation. Such a being would be a microcosm within the macrocosm—a being with material elements, plant-like powers, animal powers, and the powers of immaterial thought and will, like angels. I believe we are such beings. If that’s true, then when God calls us to union with Himself, He is, in a sense, bringing all of creation along with us.¹⁰

How might God unite us to Himself? Here’s one idea: He might first unite Himself to us—by assuming a human nature, by incarnating. After all, this might be a fitting way to bring humans into the life of God: by God becoming man. God comes down to lift man up, or something like that.

Why so? If only because, as Norris Clarke explains, “to share our journey with us, to show us the best and surest way to walk it, and to ensure its final transcendent success beyond this present world. This God-with-us-now becomes the great, perfected Mediator and High Priest (The Pontifex Maximum = supreme Bridge-Builder) between the entire created world and its Ultimate Source and Goal.”¹¹

Honestly, I doubt anyone could have predicted this before the startling claims of Christianity; however, looking back, I think we can see there is an undeniably beautiful fittingness to it. And maybe God would have done this no matter what, even if the world were in a perfect—or at least pain-free—state. However, the world isn’t perfect—it’s often quite terrible.

So, something went wrong. What? Why? There are plausible stories that could be told, and perhaps different versions capture parts of the larger, complete truth. Perhaps God has immaterial agents in creation—free beings who help govern the cosmos; delegates. Maybe some of these beings rejected God and caused trouble, including tempting humans toward evil. Through the sin of these beings and humans, suffering and evil spread. God allows this for two reasons. First, it respects the nature of free beings. He won’t cancel every bad choice a free agent makes, as this would undermine their nature as agents of (inherently fallible) freedom. (This aligns with another traditional principle: God guides things according to their nature, and ours is fallible.) Second, God can bring good out of evil—eventually defeating and integrating such evils into an overall greater good. Moreover, allowing these evils, including having a general policy of not constantly intervening (which might lead to the appearance of many gratuitous evils), may be the best or only way for us to recognize our spiritual disease and turn back toward God, where our ultimate fulfillment lies.¹²

The problem of evil is tough to grapple with, and it poses, in many ways, the most serious threat to the existence of an all-good God. I've said only a little here, but much more has been, and could be, said—and should be read. There are, I believe, sophisticated and adequate accounts that not only explain how the suffering we see in the world can be compatible with God's existence and goodness, but that actually show how this very world, with all its awful dark spots, can testify to God's existence and goodness. A bold claim, I know—but one that, I believe, can ultimately be cashed out.¹³

And this is where the Incarnation serves as a rescue mission. God enters our broken situation, shows He isn’t indifferent to it, and takes on the worst of it because He loves us and wants us to become morally perfect, so that we can be united to Him—our ultimate end. Perhaps this was the most fitting way for God to save us: to help us see His love and share in His suffering so that we might become righteous and holy—in a word, saved—through His incarnational initiative.

There is, of course, much more that can be said about many of these points. This account has many components, and admittedly, many of them are contested. I cannot defend all of these details now, but I will say this: Nothing in this story seems particularly implausible—at least not to me. There is nothing in it that contradicts any obvious facts of reality or contemporary science, of that I am quite confident. In fact, classical Christianity is deeply attractive precisely because, in both its philosophy and theology, it offers what I believe is the most comprehensive explanation of the widest range of experiences that require an adequate account. This includes everything from why anything exists at all, to consciousness, rationality, morality, order, stability, beauty, and yes, even suffering and evil.¹⁴

Practically speaking, Christianity adequately addresses the simplest yet deepest questions we inevitably ask—often beginning in childhood: Who are we? Why are we here? Where did everything come from? What does it mean to live a good life? How am I to achieve it? And where, if anywhere, am I going?

Most people are already familiar with the general Christian answers to these questions. Many, however, don’t believe them, dismissing them as too good to be true—a kind of wishful thinking. Over the years, I’ve come to see it differently: given the plausibility of the classical worldview, it strikes me as too good not to be true. After all, "Christianity, in all its complexity, ultimately comes down to the striking thesis that fundamental reality is irreducible love in powerful, welcoming relationship."¹⁵And what could be better than that?

1. I don’t want to suggest this is the only philosophical Big Picture that might anticipate something like Christianity. Just one.

2. I take the Trinity to be another essential Christian commitment, though not one that can be proved philosophically—only defended against charges of incoherence. Nevertheless, I maintain that the Trinity is compatible with classical theism, including divine simplicity. For more on this, see my conversation with James Dolezal.

3. As it happens, the traditional understanding of matter is itself just a principle of limitation and individuation.

4. For an argument as to why there can be just one being whose essence is its existence—and some motivation for the “thick” theory of existence in general—see my recent conversation with Gaven Kerr.

5. Geach contrasts this with the "predicative" use of adjectives, which have a standalone meaning, such as "red." See Geach, Peter. "Good and Evil."

6. This point about relevance is critical. As I clarify in my book (I’ll quote myself, because hey, somebody has to!): “While Aquinas and others maintain that being and goodness are convertible—which is true—it doesn't follow that simply acquiring more being in an absolute sense leads to perfection. That would imply, somewhat absurdly, that a person should strive to become as fat as possible (since more being equals more goodness, right?). Instead, it is being in accordance with our specific potential that matters most—being that aligns with the most relevant features of our nature. Thus, becoming gluttonous and obese is irrational (due to the negative health consequences), and in doing so, we fail to achieve our highest good in the areas that matter. Aquinas explains this by distinguishing between first and second actuality. In terms of first actuality, a human is good simply by existing—there’s no question there. But in terms of second actuality, a human is good to the extent that they actualize their rational capacity, since rationality is their species-defining potential.” For a further explanation and defense of this thesis, see Stump, Eleonore. "Aquinas’s Theory of Goodness." The Monist 105, no. 3 (2022): 393–417.

7. Here is an excellent essay on analogy or the use stretch-concepts, by Norris Clarke.

8. The diffusiveness principle is an ancient idea that finds support among contemporary philosophers such as Norris Clarke, Norman Kretzmann, and Joshua Sijuwade. Michael Liccione provides a helpful summary:

"Consider a key use Aquinas makes of the venerable Neoplatonic principle bonum est diffusivum sui et esse—'the good is diffusive of itself and being.' According to this, any action performed by an agent entails the agent’s communication of its goodness: the communication of being and goodness proceeds from goodness. This is evident both from the nature of good and from its concept (ratio). The good of anything is its act and perfection, and something acts insofar as it is in act. By acting, it diffuses its being and goodness into other things... For this reason, it is said that 'the good is diffusive of itself and being.' This diffusion applies to God, for He is the cause of being for all other things (SCG I.37.5).” Liccione, Michael. "Mystery and Explanation in Aquinas’s Account of Creation." The Thomist: A Speculative Quarterly Review 59, no. 2 (April 1995): 223-245.

9. Despite my belief that one cannot offer a “metaphysical proof” of the Trinity, the classical theistic understanding of God as fully actual and self-sufficient yet communicative of His goodness obviously fits well with Christian revelation that God exists in a relationship of love within Himself—Father, Son, and Holy Spirit. The Trinity is the ultimate expression of relational goodness, which then extends to creation and humanity, particularly in Christ’s incarnational mission to bring people into this divine communion. Another clue, perhaps.

10. When I first encountered idea in Christian account, I thought: Woah! It struck me as marvelous—and it still does.

11. The One and the Many, 307.

12. Peter van Inwagen offers a powerful response to the problem of evil along these lines The Problem of Evil.

13. In addition to van Inwagen’s book, I recommend very highly Eleonore Stump’s Wandering In Darkness.

14. Of course, much of this data is explained by “bare” classical theism, though I suggest that Christianity can be seen as a natural consequence of classical theism. I discuss this further in my book The Best Argument for God. Either way, I believe Christianity provides a fuller, more comprehensive picture than classical theism alone, particularly regarding the significance of relationship and love as fundamental to reality. Moreover, it is the only paradigm I’ve found that offers a truly adequate—and seriously hopeful—response to the problem of suffering.

15. Said by Eleonore Stump in different ways across her work but most recently in her book The Image of God.