Christianity Can’t be Deduced from Nature

I know not with what weapons World War III will be fought, 
but World War IV will be fought with sticks and stones.
— Albert Einstein
Suppose Einstein’s catastrophic World War III happened and civilization was destroyed. After a thousand years, civilization returns to roughly our level of scientific awareness.
After losing all knowledge of optics and thermodynamics and gravity, this naive society has re-discovered it—the very same laws of optics and thermodynamics and gravity that we have now. Ditto for relativity or e = mc2 or F = ma or any other scientific law or theory.
Obviously, these post-apocalyptic humans would have different terms and ways of representing things—consider how mathematical symbols, numbers, punctuation, paragraph breaks, and even spaces have evolved over the centuries. But whatever notation they invented would be synonymous with our own since they would simply be descriptions of the same natural phenomena.
Does it work that way with religion?
By contrast, imagine that all knowledge of Christianity were lost. A new generation might make up something to replace it, since humans seem determined to find supernatural agency in the world, but they wouldn’t recreate the same thing. There is no specific evidence of the Christian God around us today. The only evidence of God in our world are tradition and the Bible. Eliminate that, and Christianity would be lost forever.
There would be nothing that would let this future culture recreate Christianity—no miracles, no God speaking to them, no prayers answered, no divine appearances (unless God decided to act more overtly than he does today). Sure, there would be beauty to wonder at, great complexity in the interwoven structure of nature, frightening things like death and disease for which they would need comfort, riddles within nature, and odd coincidences. People then, like they do now, would likely grope for supernatural explanations, but starting from scratch you could invent lots of religions to explain these things. There is no evidence or observation that would guide them to any specific supernatural dogma that we have today, except by coincidence.
Christians today come to their beliefs because someone initially told them of Christianity. If no one told you, you couldn’t figure out Christianity on your own, which is quite the opposite from how science works.
Note that morality doesn’t need rediscovering. Naive people don’t need to be told that you oughtn’t treat someone else in a way you wouldn’t like to be treated. That doesn’t mean that everyone in a post-apocalyptic society will act with compassion and generosity, just that they don’t need to be taught this.
The Bible weighs in on our thought experiment. It claims:

Since the creation of the world God’s invisible qualities—his eternal power and divine nature—have been clearly seen, being understood from what has been made, so that men are without excuse” (Romans 1:18–20).

And yet, without God informing humanity of his existence, Christianity could never be recreated. Worship of one or more gods, sure. But not Christianity.
Take Two
Here’s a variation on this thought experiment. Imagine the post-Christian society comes across a library from our day from which they find information about 20 religions that are popular today. This information spreads and civilization gradually adopts these new religious options. What is the likelihood that Christianity would come out on top again? Not very.
Let’s acknowledge that Christianity is sticky. If its message were a dud—that is, if it didn’t give people what they were looking for, at least to some extent—it would have faded away. But now we’ve turned our backs on the question of truth and are squarely in the domain of marketing, considering which features of religion satisfy people’s emotional needs and which are turn-offs.
The grocery store of religion
This is religion as breakfast cereal. Some new cereal brands last for a few months and are then withdrawn while others remain appealing (often adapting to changes within society) over the decades. Christianity is simply the Cheerios of religion. Like any successful brand in the marketplace, Christianity has spun off many variants—as if Protestantism were the equivalent of Honey Nut Cheerios, Mormonism as MultiGrain Cheerios, and Pentecostal as Cinnamon Burst Cheerios.
What can you say about a religion that can’t be recreated from evidence at hand today? About a religion whose god is knowable only through tradition? You can say what applies to all religions: we can’t prove that it’s manmade, but it gives every indication of being so.
I’ll end an observation by Thomas Paine in The Age of Reason, still relevant 200 years after he wrote it.

The study of theology as it stands in Christian churches, is the study of nothing; it is founded on nothing; it rests on no principles; it proceeds by no authorities; it has no data; it can demonstrate nothing; and admits of no conclusion. Not any thing can be studied as a science without our being in possession of the principles upon which it is founded; and as this is not the case with Christian theology, it is therefore the study of nothing.

Related post: Historians Reject the Bible Story.

There is no god, and that’s the simple truth.
If every trace of any single religion were wiped out
and nothing were passed on,
it would never be created exactly that way again.
There might be some other nonsense in its place,
but not that exact nonsense.
If all of science were wiped out,
it would still be true and someone would find a way to figure it all out again.
— Penn Gillette

 (This is a modified version of a post that originally appeared 2/27/12.)
Photo credit: Wikimedia
 

Bloggers: Want a Free Review Copy of My New Book?

(Update: I don’t need any more reviewers for Christmas 2013!)
My new book will be released on November 25, but I’d like to get review copies to bloggers, journalists, or anyone else who might be able to give the book a good word.
A Modern Christmas Carol is an homage to the Dickens classic in which a modern televangelist gets the Scrooge treatment. He’s visited first by his long-dead partner, and then three ghostly guides. During his journey, he’s forced to question his faith and witness the impact of his uncompromising message on viewers. Back home on Christmas Day, he makes amends with far-reaching consequences.
Many Christians and atheists might enjoy seeing a televangelist get his comeuppance, but the book is more than that. There is a challenge here that will attract thoughtful readers who enjoyed the intellectual workout of books such as C. S. Lewis’ Mere Christianity or Richard Dawkins’ The God Delusion.
It’s a novella like the original, so it’s a quick read. Though it’s not quite Christmas season, I wanted to give any reviewers time to read it.
Are you interested in Christianity’s role in society or in the debate between Christians and atheists? Would you be able to read the book and write a review? Is so, I want to mail you a free copy. I’m hoping to get any reviews published around Thanksgiving. Short blurbs (in which I could acknowledge and link to your blog or book) would also be very welcome.
If you’re not able to publish a review, I’d appreciate your passing this link along to someone who could. Can you think of anyone with a blog, a newspaper column, or similar standing who might be interested? The offer of a free review copy extends to them as well.
Thanks!

Rebutting the “God is Simple” Argument

In The God Delusion, Richard Dawkins said, “God, or any intelligent, decision-making calculating agent, is complex, which is another way of saying improbable.”
Is God simple or complex?
Philosopher Alvin Plantinga argues that he is not complex:

According to much classical theology (Thomas Aquinas, for example) God is simple, and simple in a very strong sense.… So first, according to classical theology, God is simple, not complex.

Seriously? We’re consulting a 13th century scholar to understand modern cosmology? Modern science takes us to the Big Bang, and we need Thomas Aquinas to figure out the remaining riddles?
Here’s philosopher William Lane Craig’s input:

As a mind without a body, God is amazingly simple. Being immaterial, He has no physical parts. Therefore to postulate a pure Mind as the explanation of fine-tuning is the height of simplicity!

So anything that isn’t physical is simple? Sure—something that isn’t physical is maximally simple physically because it doesn’t exist physically. It has no gears or cams or levers. But that doesn’t help us with immaterial things, whatever they are. I don’t know what it means to be an immaterial mind, so I have no way of evaluating its complexity. Incredibly, neither apologist gives any evidence of the claim that God is simple. They seem to have no way of evaluating its complexity either and propose we just take their word for it.
Of course, science has shown that complex can come from simple. For example, we see this in the formation of snowflakes, in erosion, in weather, in chaos, or in evolution. From a handful of natural rules comes complexity—no intelligence required.
But we’re talking about something quite different—an intelligent creator. And in every creative instance we know of (the creation of a car, the creation of a bee hive, the creation of a bird’s nest), the creator is more complex than the creation. Plantinga’s God would be the most stupendous counterexample to the axiom that, in the case of designed things, simple comes from complex, and yet we’re supposed to take this claim on faith.
A resolution to the problem
But there’s a way to cut through all this. Is God as simple as Plantinga or Craig imagine? Then demonstrate this. Make us one. Humanity can make complex things like a microprocessor, the worldwide telephone system, and a 747, so making this “amazingly simple” thing shouldn’t be hard. Or, if we don’t have the materials, they can at least give us the blueprints.
But, of course, they will fail in this challenge and must admit that they have no clue how to build a god. In that case, how can they critique the simplicity of such a being? Now that their argument that God is simple has evaporated, we’re back where we started, and Dawkins’ argument stands: a complex God is improbable.

Why are we asked to pray after a disaster? Hasn’t god made it clear that he doesn’t give a f**k? — Frankie Boyle

(This is a modified version of a post originally published 1/2/12.)
Photo credit: Wikimedia

“God Did It” Explains Everything … or Maybe Not

Apologist Greg Koukl is the gift that keeps on giving. In his “Is Consciousness an Illusion?” podcast, he talked about Daniel Dennett’s 2006 book Breaking the Spell.
Let me first seize the opportunity to agree with something. Koukl says, “Reality is the kind of thing … that will injure you if you don’t take it seriously.” It’s good to see us sharing the goal of seeing reality clearly.
Unanswered questions within science
But we don’t agree on everything. Koukl said:

[Dennett has] made a claim in this book about something that is very, very difficult for a materialist to deal with that makes sense completely within a Christian worldview.

The “something” is consciousness. So Koukl says that the scientist has a tough time explaining consciousness, but it’s easy for the Christian.
While it’s true that science has much to discover about consciousness and how it works, I don’t see anything in particular that ought to keep the naturalist up at night. Science has an unanswered question—big deal. Science has lots of unanswered questions. It also has a marvelous track record for answering them.
But what trips me up here is the idea that the Christian worldview adds to the discussion. How does God explain anything?
Let me make clear that I can never prove that God didn’t do something. For example, let’s consider a few claims about God by Pat Robertson. He said that God is “lifting His protection from this nation” to allow terrorist attacks (2001). And that Hurricane Katrina might be God’s doing (2005). And that the people of Haiti made a pact with the devil, in response to which God allowed the earthquake that killed 300,000 (2010). These are assertions without evidence (and, in the case of Haiti in particular, of much contrary evidence), but I can’t prove that “God did it” is false.
The uselessness of the Christian’s ultimate explanation
The fact is, “God did it” can explain everything. As a result, it explains nothing.
“God did it” is simply a repackaging of “I don’t know.” It tells us nothing new. I’m no smarter after hearing “God did it” than before. It tamps down one set of questions, but others pop up: Who is God and how does he act in the world? Is he one of the thousands of gods that humans have already formed religions around or someone new? Why did God do what he did? What natural laws did God use to do it, and what laws did he suspend? How can we communicate with him? And, most importantly: how do we know that there was a supernatural cause and not a natural one?
The Christian must ask: What would falsify my position? If it’s unattainable or if you’ve so protected your belief that nothing could perturb it, you’ve left the domain of evidence. When your God belief is supported no matter what happens, be honest with yourself and admit that you just believe and drop the pretense that you’re following evidence or being scientific.
Contrast that with this observation from Marvin Minksy:

As scientists, we like to make our theories as delicate and fragile as possible. We like to arrange things so that if the slightest thing goes wrong, everything will collapse at once!

Not all claims are equal
Think about the size of various claims. The claim “1 + 1 = 2” is not controversial. The claim “I had a sandwich for lunch” is unsurprising, and thorough evidence could be provided to back it up. But the claim “There is a being that created the universe” is without scientific precedent—that is, science knows of no supernatural anything, let alone a being that could create the universe. I can think of no bolder claim than “God did it.” It’s baffling to me how apologists can toss out that immense claim and simply let it hang there, supported by nothing more than wishful thinking and tradition.
“God did it” doesn’t do it. It satisfies only those who want their preconceptions affirmed.
But let me take a step back for a moment. I’m treating this claim with the dignity due those that make testable pronouncements about reality. Perhaps that’s my mistake—if it’s simply a theological claim divorced from reality, fine. In that case, it’s a claim to be taken simply on faith, with no pretense of evidence or verifiability, and I have no use for it.
Supernatural vs. natural explanations
Let me end with a song, “Tell Me Why” by Pat Benatar*, which nicely makes the “God did it” claim.

Tell me why the stars do shine,
Tell me why the ivy twines,
Tell me what makes skies so blue,
And I’ll tell you why I love you.
(refrain)
Because God made the ivy twine.
Because God made the stars to shine.
Because God made the sky so blue.
Because God made you, that’s why I love you.

This Christian explanation is poetic, but for those of us who prefer to actually understand the world, Isaac Asimov has a new and improved refrain:

Nuclear fusion makes stars to shine,
Tropisms make the ivy twine,
Rayleigh scattering make skies so blue,
Testicular hormones are why I love you.

I’ll stick with the discipline with the track record for explaining reality.

The man who prays
is the one who thinks that god has arranged matters all wrong,
but who also thinks
that he can instruct god how to put them right.
― Christopher Hitchens

(This is a modified version of a post that originally appeared 12/28/11.)
Photo credit: Wikipedia
*Lyrics © Warner/Chappell Music, Inc., Sony/ATV Music Publishing LLC, EMI Music Publishing.

A Pro-Christian Argument For A Change: TAG

This is an excerpt from my novel, Cross Examined: An Unconventional Spiritual Journey.
The Players:

  • Rev. Samuel Hargrove is a well-known pastor and debater. 
  • Prof. Putnam is taking the atheist side in the debate. He’s a physics professor from USC.
  • Paul Winston is Samuel’s 23-year-old acolyte. At this point in the story, he’s still shaken by the death of his fiancée in the earthquake, a few weeks earlier.

The Setting: Los Angeles in 1906, just after the San Francisco earthquake. We’re in Samuel’s church, watching his annual apologetics debate.
Samuel stressed to the audience the importance of understanding apologetics. He listed several Bible verses to support this, with special attention to 1 Peter 3:15, “Be ready always to give an answer to every man that asketh you a reason for the hope that is in you.” He noted that Genesis does not begin with an argument for God’s existence but instead takes this for granted, and Samuel justified this with another verse: “The invisible things of God from the creation of the world are clearly seen so that men are without excuse.”
“You want to see the hand of God?” Samuel said. “Then just look around you. These are powerful arguments, but again they satisfy only believers like most of us. Today we will put those arguments aside. The tools today are reason and logic, but these are friends of the Christian. We have nothing to fear from them; in fact, we invite critique because we must know that Christianity is valid and strong. Questioning is good. The apostle Paul said that if our faith in Christ is misplaced, then ‘we are to be pitied more than all men.’ So bring on the attack. Our fortress is built on the Eternal Rock.”
Samuel wrapped up his introductory remarks by thanking his opponent for participating. He then stated the topic of the debate: “Does God exist?” with Professor Putnam taking the negative position. The professor smiled slightly in acknowledgement and took in the audience with a relaxed face.
If Putnam didn’t yet know that he was playing Samuel’s game, on Samuel’s court, and by Samuel’s rules, he found out soon enough. Samuel asked the professor’s permission to begin the debate with an informal chat to explore the issues for the benefit of the audience. This was unexpected, but the regulars in the audience knew to expect that. Whether preaching or debating, Samuel was rarely boring.
With both men seated at the table, Samuel began by asking for the professor’s agreement to a logical statement. The professor brushed at something on the sleeve of his gray suit and identified it as the Law of Noncontradiction. Samuel threw out another one. Again the professor made a quick identification: this time, the Law of the Excluded Middle.
Samuel looked delighted as if a precocious child had answered a question above his age. “Clearly you are familiar with the laws of logic—surely much more so than I.”
“That’s only to be expected. Logic is what I base my research on.”
“Then let me ask you this: why are these laws true? Why should there be a Law of Noncontradiction?”
The professor looked up, then crossed his arms and rocked slightly in his chair. He opened his mouth, paused, and then closed it. Paul slid forward in his seat as he watched the man’s unease. Finally, the professor said, “We use logic because it works.”
“It does indeed work, but why? Why should the universe be bound to obey these laws? Surely the reason logic is true is not ‘just because.’ ”
Again a pause. The professor, slight and scholarly behind his glasses, made quite a contrast at the same table with Samuel, tall and broad and with a more-than-generous voice. In his modest tone, the professor said, “Well, logic is a convention.”
“A convention? You mean like a custom? Are the laws of logic arbitrary so that we might have one set while the French would get along quite happily with a different set—like we measure distances in feet while the French measure in meters?” Samuel turned to the audience. “Oh, I do so enjoy the spring, when the new laws of logic come out of Paris.”
Laughter swept the audience, and Paul leaned back, grinning. Putnam pursed his lips and shook his head, and Samuel raised his hands as if in submission. “I apologize, Professor. We’re just having a little chat here, so I thought you wouldn’t mind my taking the liberty. No, of course you don’t see logic to be as changeable as fashion. We agree that logic is universal. I’m simply saying that if you can’t tell me why that is the case, I can.”
The professor leaned forward and his voice rose slightly in pitch. “We’re in the same boat. Your justification for logic is no stronger than mine.”
“Not at all. You deny the supernatural source of logic, but I don’t. Logic comes from God; it is a consequence of God. The believer can point to his source of logic, but the atheist has no justification.”
The professor swept the crowd with his hand. “Look around you—atheists are logical. Atheists are rational.”
“Yes, atheists are rational, but only because they are dishonest to their own professed principles. The irony is that the atheist must borrow from the Christian worldview to reject it. Atheists deny the very God whose existence makes their reasoning possible.”
The professor took out a handkerchief and dabbed his upper lip and forehead. “Christianity didn’t invent logic. The ancient Greeks preceded the Christians and were pioneers in logic—Aristotle, for example.”
“I agree,” Samuel said. “But that doesn’t change the fact that logic is a consequence of God’s existence. Non-Christians are welcome to use it, but it comes from God.”
“Why can’t we presume that logic is transcendent—that it’s always existed?”
“It is indeed transcendent. But that doesn’t answer the question why. Why has logic always existed?”
The professor glanced up at the ceiling before continuing. “Logic just exists. It has certain properties. It’s just a fundamental part of reality.”
Samuel smoothed his mustache with the back of his right hand. “Oh, so that’s how the game is played? All right: God just exists. God is just a fundamental part of reality. But can we just define things into existence? Of course not. No, that’s not an argument. I apologize for being so persistent, but I must return to my original question, which remains unanswered: why is logic true?”
The professor made a growling “Rrr!” sound and said, “You don’t understand.” He paused as if collecting his thoughts and then scowled. “Reverend Hargrove, is this an interrogation or a dialogue? Will I get an opportunity to ask questions?”
“I do apologize. I have indeed monopolized the conversation. Please, Professor, go right ahead.”
Putnam rummaged through a small stack of papers, putting first one sheet on top and then another. “All right,” he said. “Why are there so many religions around the world? Doesn’t this say that each culture invents a religion to suit itself?” The audience hushed.
“The world’s many religions say that people have an innate urge to discover their Maker,” Samuel said. “This universal hunger in every human bosom points to a God who can satisfy that hunger.” Paul smiled. Another point scored, and the professor’s face showed the hit.
The professor leafed through his papers again. “Well, answer me this. The Christian God is described as a loving god. And yet we have disease and famine and war. Wouldn’t such a god put an end to this, if he existed?”
“Who knows what disasters might have happened but haven’t because of divine providence? We don’t see the headline ‘Thousands not Dead Because of Disaster that Didn’t Happen’ simply because we don’t know what God has shielded us from. Indeed, it is arrogant to imagine that we are smart enough to understand, let alone critique, the actions of the Creator of the universe. And the Fall of Adam and Eve—the original sin in the Garden of Eden—explains the imperfect world we live in.”
“Rrr!” More paper shuffling. The professor’s voice became somewhat shrill and he spoke more quickly. “Tell me this: why believe the Bible? You don’t believe Homer’s Iliad. You don’t believe the ancient books of other religions.”
“The story of Jesus was written down just a few decades after the fact, and we have perhaps thousands of ancient manuscripts of the books of the Bible. This lets us recreate the original documents with great precision. And many non-Christian historians of that period document the truth of Jesus’s life outside the Bible. By contrast, we might have a biography written centuries after the death of a historical figure such as Alexander the Great, and we regard that as truth. And when you consider that the men closest to Jesus were martyred for their beliefs, surely no one would die to defend a story he knew wasn’t true.”
“Well, history is not really my area of expertise.” The professor tapped a new sheet that he had placed on top of the pile. “All right, the Bible documents slavery among the Israelites, but God does nothing to stop the practice. Given this, how can the Bible be called a book of morality?”
“First, keep in mind that the Bible documents many customs that have nothing to do with godly living; they were simply practices of tribal people in a place and time far different than our own. As for slavery, we’d still have slavery in America today if it weren’t for people like Harriet Beecher Stowe, John Brown, William Lloyd Garrison, the Quakers, and others—all Christians guided by Christian principles.”
Samuel looked over for more questions, but the professor seemed spent. The silence lengthened, and Paul felt the small man’s discomfort. He couldn’t imagine being on that stage with hundreds of people staring, waiting for a mistake, enjoying his distress.
Samuel slid his chair back. “With your permission, Professor, shall we begin the debate?” Putnam yielded with a gesture of his hand, saying nothing.
Samuel walked to the podium and began his prepared remarks, a proud oration that surveyed a number of compelling arguments. Instead of doing the same when it was his turn, the professor used his time to rebut Samuel’s opening points. That’s a bad move, Paul thought. You’ve allowed your opponent to select all the arguments. He sensed that the contest was already over and leaned forward with his elbows on his knees. He wondered if the professor had already used up his own points in his questions to Samuel. The result was that the entire debate would be fought on Samuel’s territory—and this was terrain that Samuel knew very well.
Paul took a personal interest in the progression of the debate, not just because he was rooting for Samuel, but because he had spent so long helping him prepare. Though Samuel was a natural speaker and an accomplished debater, he still took preparation for each debate seriously and this year had assigned Paul some of the research tasks. Samuel had thoroughly explained the various arguments from each side and critiqued their strengths and weaknesses. “You’ll be doing this yourself some day,” Samuel had said.
The professor gamely held up his end of the argument, but he was outmatched. His voice became thinner and he didn’t use all the time that was available to him. His eyes and gestures often pleaded with the crowd as if to ask for their acceptance of an argument he couldn’t quite put into words, one that seemed just out of his grasp. The rebuttals were often little more than “I don’t agree with you there” or “You’ll have to do better than that.”
Samuel wrapped up his final remarks. “Let me return to the original question, which, after all this time, still has not been answered from the atheist position: why is logic true? Professor Putnam says that I have no answer to this question, but I do—it’s just that he doesn’t like it. God created the world, and logic is a consequence.
“We can agree that logic is universal. It’s also abstract—in other words, it has no physical presence like a book or a table. And logic is unchanging, unlike the things we see around us that grow or decay over time. Aside from logic—and perhaps what is built on logic, like mathematics—we know of just one other thing with these properties, and that is God.
“Let me be clear that I respect the professor’s logical skill. He’s a scientist, and I’m sure he uses logic very well in his work. The only problem is that he must borrow from the Christian position to do so. By his own logic, logic can’t exist. In rejecting God, the atheist has rejected his source of logic and has therefore eliminated his ability to use it. Without its Christian foundation, this entire debate wouldn’t make sense.”
The professor had the last block of time, and he used it up like a football team that knows it’s beaten and is eager only to run out the clock and go home. When he finished, the moderator thanked both participants and the audience applauded. Samuel beamed at the crowd, while the professor collected his papers and stood to leave even before the applause was over.
The reporters left promptly—to file their stories, Paul supposed—but people milled about afterwards, seemingly eager to savor the night.
“Another sacrificial lamb, eh, Pastor?” said one man with a smile.
“I think this was the most impressive debate yet,” said another.
“You should call these the ‘Loose Canon’ debates. You know—’canon,’ like scripture,” said a third.
Twenty minutes after the debate had ended, the church was still half full of supporters. A few people encouraged Samuel to speak and the call for an encore swept through the crowd. Samuel mounted the podium in response to the curtain call and gave a short epilogue. As the audience took their seats, he emphasized the importance of apologetics to his ministry and encouraged everyone to be an ambassador.
Paul leaned back in his pew and smiled. It seemed to him that no one in the city knew more about the defense of Christianity than this man, and surely none could beat him.
Read more about the book and an extended excerpt from the beginning here.

Martyrdom has always been a proof of the intensity,
never of the correctness of a belief.
— Arthur Schnitzler

Plantinga’s Unconvincing “Evolutionary Argument Against Naturalism”

What better way to respond to atheists but to turn one of their own tools against them? That’s the approach philosopher Alvin Plantinga tries to use with his Evolutionary Argument Against Naturalism (EAAN). It’s not a new idea, and both C.S. Lewis and Charles Darwin anticipated it.
In brief, the question is: how can a human mind that’s the result of the clumsy process of evolution be trusted?
About “Darwin’s doubt,” Plantinga argues that only Christians can have confidence that their interpretation of the world is correct. Naturalists can’t prove that minds are reliable until they’ve proven that the source of this claim (the mind!) is worth listening to.
Here’s where Plantinga claims to have turned the tables:

The high priests of evolutionary naturalism loudly proclaim that Christian and even theistic belief is bankrupt and foolish. The fact, however, is that the shoe is on the other foot. It is evolutionary naturalism, not Christian belief, that can’t rationally be accepted.

He says that if evolution is true, human beliefs have been selected for survival value, not truth, so why trust them? And yet our beliefs are reliable, suggesting to Plantinga that something besides evolution created them.
Before we get into the specifics of Plantinga’s argument, let’s first establish a baseline. Plantinga and naturalists agree that humans’ needs and desires are pretty logically matched:

Feelings or desires are on the left, actions are on the right, and the arrow is the belief that a particular action will satisfy that desire.
This is straightforward. A human with the feeling of hunger has the belief that eating food is the action to take. You go toward cuddly things, you run from scary things, you get to clean air if you can’t breathe, and so on. This is the world we all know and understand.
But Plantinga says that naturalists delude themselves. He imagines the naturalist’s world in which these links are jumbled. He imagines a hominid Paul who has some problematic beliefs about predators:

Perhaps [Paul] thinks the tiger is a large, friendly, cuddly pussycat and wants to pet it; but he also believes that the best way to pet it is to run away from it.

So Paul’s instincts toward tigers keep him alive, but only by dumb luck. But unreasonable beliefs don’t stop with tigers. Plantinga imagines the naturalist’s view of the world with beliefs having no connection with reality. That is, he imagines something like this:

Paul’s response to the tiger was just a roll of the dice, and he got lucky. But Plantinga supposes that all of Paul’s beliefs are arbitrary, not just those about tigers. Some actions in this chart are benign, but some are dangerous. When Paul sees something scary, his reaction is to walk toward it. When he’s drowning, he’ll try to sleep. When he’s hungry, he’ll satisfy that need with fresh air, and so on. With his basic desires paired with ineffective methods, this guy is clearly too stupid to live.
This is where natural selection comes in. Natural selection is unforgiving, and belief sets that don’t lead to survival are discarded. Evolution easily explains why Plantinga’s Paul didn’t exist.
An article at Skeptic.com neatly skewers Plantinga’s argument with a familiar example.

If a professional baseball player [incorrectly perceived reality,] that is, if his perception of the movement and location of a baseball was something other than what it actually is, then he would not be able to consistently hit ninety-five mile per hour fastballs.

As an aside, let me admit that I have a hard time maintaining respect for those at the leading edge of philosophy. Do they do work that’s relevant and pushes the frontier of human knowledge? I’d like to think so, but when this is the kind of argument they give, it’s hard to keep the faith.
My advice to philosophers: when you get the urge to play scientist, it’s best to lie down until the feeling goes away.

If we’re made in God’s image,
then why aren’t we invisible, too?
— graffiti

Photo credit: Wikimedia