Why We Cannot Prove God Exists and That’s Okay

Why We Cannot Prove God Exists and That’s Okay September 20, 2021

In his masterful introduction to Metaphysics, Peter van Inwagen points out why the cosmic fine-tuning argument (or the “teleological argument”) is ultimately indecisive in proving the existence of an intelligent designer of the world:

As far as our present knowledge goes (aside from any divine revelations various individuals or groups may be privy to), we have no reason to prefer either of the following two hypotheses to the other:

  • This is the only cosmos, and some rational being has (or rational beings have) fine-tuned it in such a way that it is a suitable abode for life.
  • This is only one among a vast number of cosmoi (some of which are–a statistical certainty–suitable abodes for life)

We do not know whether the fine-tuning of the one cosmos we can observe is due to the action of a rational designer (or designers) or is rather the result of chance and an observational selection effect.

Peter Van Inwagen, Metaphysics, 216

In other words, it is impossible to decide on rational calculation alone, whether the existence of an intelligent designer of the universe (God) is true as opposed to that of a world-generating multi-verse, which produces, inevitably, life-permitting “cosmoi” based on some intersection of chance and necessity. At most, according to Van Inwagen, we can say that both positions are about the same. Again, on a purely rational calculation.

My Early Experience with Christian Apologetics

Shortly after I got saved (yes, “got saved”) I found myself enthralled with Christian apologetics. My first book was Lee Strobel’s The Case for Christ (yes, “The Case for Christ”), which I read in a 48-hour period sitting in a chapel at Bagram airbase (oh the days when Bagram was a safe place to read books on Christian apologetics!). Shortly after reading that book I found what is considered by many the mother lode of apologetic resources, the online treasure trove of William Lane Criag’s debates against atheists and agnostics of various philosophical dispositions (with the exception of that coward, Dawkins!). I watched almost every one. Once I heard the Kalam Cosmological argument articulated the 50th or 60th time, I knew we (us Christians) had it in the bag: KCA = QED.

When it came to demonstrating Christianity more specifically, however, that always seemed a bit trickier. Arguments for the reliability of the scriptures, the bodily resurrection of Jesus, the integrity of the transmission of the biblical texts, etc., seemed to run aground of more concrete counter-evidences than those of natural theology. Nevertheless, if God existed, then clearly Jesus and the Gospel were the most logical, most probable and certainly most desirable next step. Or at least so my newly converted heart believed.

At this point, I expect some progressive or former Christians might assume I am going to switch gears and tell a tragic, yet liberating, tale of deconstruction, deconversion and rampant doubt in the project of Christian apologetics. Unfortunately, that assumption would be horribly wrong. I hate to disappoint, but not really. My personal deconstruction story occurred years ago, starting around the age of 14. It ended when God reconstructed my faith at the age of 34 (after many years of wandering in a wood darkly).

However, at this stage in my reading and research, and in my faith journey, I have come to conclude that there is no demonstration for either God’s existence or Jesus’ claims that can be achieved through purely rational means. Apologetics has its clear limits. Of course, this thought is not novel and is, in fact, rather hackneyed. No theologian worth his or her salt over the many centuries of the Church’s history ever held that rational argument alone could convert the human person to God, even if some very brilliant theologians did believe that the human person could know rationally (as in justified, true belief) that God did exist. However, maybe those theologians (Aquinas) were wrong on this point. Perhaps we cannot, by reason alone, know that God exists. Perhaps we can only suspect God exists. However, perhaps this suspicion is itself by design.

Warranted Christian Belief

Alvin Plantinga, another Christian philosopher and former colleague of Van Inwagen, has been known for devising a somewhat different kind of Christian apologetic. It is one that does not seek to demonstrate or prove God’s existence or even show it being more likely than not, pace the likes of Aquinas or Richard Swinburne. Rather, Plantinga’s warranted Christianity has a more modest goal, to show that Christianity is not irrational to believe. Instead, like perhaps other worldviews, Christianity is warranted to hold to, to have faith in, regardless of whether it is de facto true or not.

If one finds oneself believing in God or “the great truths of the Gospel,” the atheist, skeptic or non-Christian co-religionist cannot assume that that basic belief in God, or even in Jesus Christ, is somehow invalid. A man sits above the Amalfi coast at sunset and notices, apart from any rational calculation, he finds himself believing in a Creator God. Can the atheist demonstrate that that belief is irrational or not oriented toward truth? He cannot. Can the man know that a Creator exists before going through a long process of deliberation, critical assessment and deductive argumentation? He can. Just as he knows without making an argument for it that it is an actual sunset he is perceiving and not some elaborate Hollywood stage set. It is a basic belief formed in a proper way, i.e., perceiving the grandeur of creation and responding to it.

A woman walks into a church and seeing a majestic image of the crucified Christ is overwhelmed by His loving presence. That this belief in Jesus or His Gospel of forgiveness is irrational, as we know from history, no one has been able to prove. Hume probably came closest, but he has been rebutted in his own day and every day since his Dialogues Concerning Natural Religion (1779). Further, other worldviews that posit explanations for belief in God, like Marxism and Freudianism, are no better explanations than Calvin’s view of their being an innate sensus divinitatis in every person that God Himself has implanted.

On Plantinga’s view, the Christian who has warrant can have knowledge about God and Jesus in a way that excludes having to possess epistemic justification grounded in various evidences or arguments (think the thief on the cross). But since no one can agree on what justification is anyway (think Edmund Gettier), does it really matter? If there is a design plan to the human person and if the human person, on average, functions according to that plan, then we would expect many people to have convictions about God, i.e., about their designer. And this is exactly what we find throughout human history and human culture, the vast majority of people having beliefs about and in God.

Moreover, this warranted belief leaves room for some other source of knowledge, a divine source that itself cannot be reduced to mere rationality or the sum of justified propositions. That source is the Holy Spirit. And, this Holy Spirit is personal. Further, being personal, He is not understandable in the way we might understand a problem of mathematics or its corresponding proof.

Van Inwagen’s parenthetical expression in the above quote, “(aside from any divine revelations various individuals or groups may be privy to)” makes similar room for this very theological space. Ultimately, it is only a theological apologetic for the Christian faith, one not irrational but supra-rational, and not unhistorical but supra-historical, that can compel us to belief both in God’s existence and in Jesus’ Lordship. The rational or epistemic doubt is itself part of the design plan so that God alone can be glorified in the person coming to a true belief and saving faith. No one will, in the end, be able to attribute their belief in God or their salvation to their own intellectual brilliance or rational powers of inference.

Alvin Plantinga: Christian Belief is Warranted

God Always Leaves Us With a Choice

That there is no QED for God or for “the great truths of the Gospel” may disconcert some Christians who want total epistemic certainty about God and His great truths. However, given the revelation found in the Bible, why would we expect such epistemic certainty? It seems, if anything, we should not expect it. What we should expect, given the Bible’s witness to its Author, is a persistent degree of epistemic uncertainty, mixed together with a variety of evidences or clues that point to God. What we never see in the Bible, however, is total demonstration.

Consider Jesus’ own words in Matthew’s account when asked by disciples of John the Baptist about his [Jesus’] identity:

Go and report to John what you hear and see: the blind see, the lame walk, those with skin diseases are healed, the deaf hear, the dead are raised, and the poor are told the good news. And, if anyone is not offended because of Me, he is blessed.

Jesus leaves some epistemic space for John to answer his own question. After all, Jesus could have simply appeared to John in His prison cell  and overwhelmed him in that dank and dark place with glorious light (perhaps both physical and spiritual light). Instead, however, he performed miracles in front of others and told them to report those miracles to John (the oral testimony of trusted witnesses). So, even John the Baptist, the greatest of the prophets up to his day, was left with some room to make a choice, a decision, about who Jesus was, even if he strongly suspected Jesus was the messiah.

Our Biases Effect Our Decisions

We might say John had a pre-rational bias in favor of Jesus, however. After all, they were cousins and something happened at that baptism in the Jordan. But, biases can go in both directions: toward or against a belief. We should note, therefore, that it was also not very conducive for John’s well-being to preach what he did. He may have had just as much pre-rational bias to not declare the coming day of the Lord as he did to do so. Given the four Gospel accounts of his ministry, it seems it took a fair amount of courage for John to fulfill his role. After all, assuming the mantel of prophet in Israel had quite a long history of pain and suffering attached to it.

Alternatively, in the very next passage, Jesus upbraids the Pharisees who rejected both John’s prophetic warning about the coming messiah and Jesus own testimony about Himself:

To what should I compare this generation? It’s like children sitting in the marketplaces who call out to each other

We played the flute for you,
but you didn’t dance;
we sang lament,
but you didn’t morn!

For John did not come eating or drinking, and they say, ‘He has a demon!’ The Son of Man came eating and drinking, and they say ‘Look, a glutton and a drunkard, a friend of tax collectors and sinners!’ Yet wisdom is vindicated by her deeds.

In short, God provided various and even contrary evidences to those who said they knew Him. On the one hand, God sent an ascetic prophet in the vein of the prophets of old, to forewarn of judgment and the urgent need for Israel to repent. But that form of evidence was rejected by many of Israel’s leaders. John’s lament over Israel was dismissed and his approach deemed to be demonic.

Then, when the Messiah Himself arrives and provides a very different kind of evidence, working miracles on behalf of sinners and tax collectors and preaching a message of mercy that too is rejected. The same group of people dismiss evidence for both the wrath and the mercy of God. Demonstrations of God’s judgement and God’s long-suffering are rejected by those who claim to know Him. What ultimately determines who believed in Jesus and who did not, was not their reason or their inference to the best explanation. There are biases at play in the will of man that go far deeper than rational thought. The Pharisees were full of such biases, like biases against sinners and gentiles.

In sum, God can, and does, offer different kinds of evidence to show who He is and what He has in store for us. However, even in presenting very different kinds of evidence, God leaves it open to those receiving that evidence to make their choice, a choice that lies in the will. And, some will reject all the evidence, regardless of whether it is evidence of this kind or of that kind. And so it is today, even with evidences like that of the fine-tuning of the universe. It could be this way or it could be that way, if reason alone is our only guide. What decides which way we will choose is not our reason but our biases and God.

As Van Inwagen puts it, either the source of our life-permitting universe is something like “Chaos,” an impersonal universe-generating mechanism, or it is something like “Logos” a personal, intentional Creator who has purposes for His creation (216-217). There is no way to decide, however, based on our rational considerations alone.

A Contemporary Analogy

Let’s consider one final analogy to make our point, which is, that the ultimate apologetic is, and only can be, theological. This itself means the only defense of Christianity that ultimately works has its source directly in God. Rationally speaking we can only come to something like agnosticism with a suspicion that God exists and that He has intentions for our lives. More fundamental to where we wind up is our biases and God Himself.

As opposed to the skeptical, yet religious, Pharisee of Jesus’ day let’s instead consider today’s modern skeptical philosopher.  The question today is not the identity of Jesus in the context of 1st-century Palestinians already committed to both the reality of the divine as well as divine revelation. For them, the question was only one of “who was Jesus” in light of prior revelation about God. Today, however, the question is one of “Is there a God” at all, and, if so, has anything about Him been revealed? And then, of course, who is this Jesus if there has been a revelation?

In the same chapter on the fine-tuning argument, Van Inwagen quotes the incredibly self aware philosopher and atheist, Thomas Nagel. Nagel, with a lucidity and candidness that is rare, proposes there is more going on than mere rational doubt when it comes to the proposition of God’s existence:

[A fear of religion] has large and often pernicious consequences for modern intellectual life. In speaking of the fear of religion, I don’t mean to refer to the entirely reasonable hostility toward certain established religions and religious institutions, in virtue of their objectionable moral doctrines, social policies, and political influence. Nor am I referring to the association of many religious beliefs with superstition and the acceptance of evident empirical falsehoods. I am talking about something much deeper-namely, the fear of religion itself. I speak from experience, being strongly subject to this fear myself: I want atheism to be true and am made uneasy by the fact that some of the most intelligent and well-informed people I know are religious believers. It isn’t just that I don’t believe in God and, naturally, hope that I am right in my belief. It’s that I hope there is no God! I don’t want there to be a God; I don’t want the universe to be like that.

Thomas Nagel, The Last Word, in Van Inwagen, Metaphysics, 218-219 [emphasis added]

Nagel openly admits to an attitude that perhaps is not all that different from the attitude of the Pharisees who Jesus confronted with miracles and with (according to those same Pharisees) inappropriate moral behavior. The Pharisees, like the contemporary, skeptical philosopher, did not want Jesus to be God. They did not want a “universe like that.” They thought they already had things figured out and then they were confronted with a whole new revelation that didn’t fit their sensibilities. They had their biases, and then this revelation threatened everything they thought they knew and which they held dear.

Today’s contemporary philosopher may share in that Pharisaical attitude, saying to herself: “this could be true, but there is something about it that goes against my biases, my more visceral inclinations. It is for this reason that I opt for the second option of the fine-tuning argument (a universe generating machine) than the first one.” And so great minds like those of Plantinga or Van Inwagen on the one hand, or Nagel and Penrose on the other, will not think alike. But, it will not be because of any great disparity in their powers of rational deliberation or critical thinking. It will be because of other, not irrational, but a-rational reasons.

Conclusion: Apologetics is A Theological Endeavor

Kevin Vanhoozer has defined theology simply as “speaking well of God.” Ultimately the best we can do as Christians is to follow his advice. While Christian apologetics has a long history of presenting evidence and arguments to compel the rational faculties, most Christian apologists know the main purpose of this endeavor is to strengthen the faith of those who already believe and to weaken the faith of those who do not.

Very few things in this world can be demonstrated with the same degree of certainty as “2+2=4.” However, once we realize that this is part of God’s design, we realize that it is part of His design because God is personal. Further, because God is personal, to know God is very different from knowing that Paris is the capital of France, that dinosaurs once walked the earth or that nothing can be both red all over and green all over at the same time. The two German words, wissen and kennen, both translatable as “to know” in English, capture this distinction well. To “know” God is not “etwas über Gott zu wissen” rather it is “Gott zu kennen und zu kennelernen.”

It just is this way because that is the way God is. The only way to know Him is to meet Him personally and to desire to be with Him upon that meeting. Our faculties of reason alone are simply insufficient for this potential to become actual. Because of this, apologetics is ultimately not an anthropological endeavor, it is theological one.



Plantinga image: Jonathunder, CC BY-SA 3.0 <>, via Wikimedia Commons

About Anthony Costello
Born and raised on the South Side of Chicago to a devout and loving Roman Catholic family, I fell away from my childhood faith as a young man. For years I lived a life of my own design-- a life of sin. But, at the age of 34, while serving in the United States Army, I set foot in my first Evangelical church. Hearing the Gospel preached, as if for the first time, I had a powerful, reality-altering experience of Jesus Christ. That day, He called me to Himself and to His service, and I have walked with Him ever since. You can read more about the author here.
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