How to Debate an Atheist

Atheism has become the dominant thought amongst intellectuals in the past century and has been around longer than most people think. For over 2000 years, it was based on philosophical arguments that can roughly be summed up as the atheist saying, “I don’t know how ‘X’ came to be, but you can’t prove it came from God.” This mindset has been highly effective because it places the burden of proof on the theist to prove the positive of God’s existence, which, superficially, is impossible to do –  because no evidence exists that provides “proof” that can be independently verified and repeated at a five-sigma (5σ) confidence level and above that God is real.

During the Age of Enlightenment in the 18th century, atheists were no longer content to use philosophical arguments and started using positive claims that basically said, “‘X’ proves God does not exist.”

Most recently, the highly influential New Atheism spearheaded by Dawkins, Harris, Dennett, and Hitchens has modified the positive arguments, but reinforced and justified a dangerous trend that started in the late 20th century that roughly states, “Because you do not accept that ‘X’ proves God does not exist, you are not credible and must not be allowed to be in a position of influence over others.”

The New Atheism mindset has had an enormous effect among atheists in positions of power in academia: For the “thought crime” of believing God exists, theist scientists have actually been blocked from jobs and tenure, they have been prevented from getting their works funded or published, and many have actually been terminated from their jobs. One now sees university campuses where openly theist professors are becoming rarer by the year, especially among those who do not have tenure—even in supposedly religious institutions. To New Atheism, science and scientific credibility are solely the domain of atheism and no one else.

Ground Rules

Before a theist and atheist engage in debate or dialogue, both parties need to agree on the basics. What constitutes pass/fail for a given item as to whether it supports the notion of God’s existence or not? Should the standards of evidence of three-sigma (3σ) to five-sigma (5σ) that all branches of science use be good enough or should the theist be held to a harsher standard. If so, why, when belief doesn’t affect our physical world? How will evidence be valued and weighted? How will individual samples be added together? (For example, are three 2σ pieces of evidence to be calculated as “2σ × 2σ × 2σ = 6σ” or another value?)

What will it take for the atheist to accept the theist’s positive argument? What will it take for the theist to accept the atheist’s positive argument? Which subjects and arguments are valid and which are invalid?

Unless these things are defined and mutually agreed upon, both parties will just talk past each other without coming to a resolution.

1. Burden of Proof

The bedrock of logic on this issue can be described as:

The burden of proof is always on the one making a claim. When the claimant is challenged to back up the declaration, the proper response is to provide evidence, not attempt to shift the burden of proof onto the skeptic.

If I claim to bench press 450 pounds (204 kg), the burden of proof is on me to prove I can do it. It is not for me to challenge the skeptic and demand he or she prove I cannot do it.

Similarly, believers who claim “God” is responsible for “X” become responsible for providing evidence for their belief in a manner that the skeptic may accept. And whatever explanation must be shown not to have an alternative cause of greater or equal probability.

All branches of science follow this standard, which can also be summarized as:

Insufficient evidence = No belief

Sufficient evidence = Belief

If this standard is good enough for all branches of science, it’s good enough for any theist-atheist debate.

2. Probability Values Are not the Same

Not all pieces of evidence have the same probability values. It is provable that gravity exists; it is plausible that she passed the exam; it is possible for you to win the lottery. In simplistic terms:

Provable = 100% certainty

Plausible > 50.1% up to <99.9% likely

Possible < 50% likely

Statistics uses confidence intervals represented by the sigma symbol (σ) to denote likelihood:

Figure 1: Normal Data Distribution Statistical Probability Table (Image Credit: Edward K. Watson, PJ Media)

What then constitutes sufficient evidence to be considered “proof”? Particle physics, one of the strictest of disciplines, uses five-sigma (5σ) as sufficient likelihood that something real is discovered. Different organizations and disciplines use different standards, with some lower, and higher than 5σ. I personally use 5σ for proof:

If something is 99.99994% likely, that’s good enough for me to function as if the issue is indisputably proven using the scientific process.


Figure 2: Different Levels of Statistical Likelihood for Belief (Image Credit: Edward K. Watson, PJ Media)

I’ve already conceded that independently verified proof of God at a five-sigma (5σ) level and above does not exist (and Christians shouldn’t want it to exist because any indisputable “proof” removes the need for faith and any sin becomes a rebellion against knowledge – just like what happened with Satan and the demons). The most convincing evidence a theist can use would be at the four-sigma (4σ) level, or at a 99.994% likelihood.

What then should an honest atheist demand to be the pass/fail criteria for accepting belief in God? Sadly, there is no uniform standard. I’ve encountered atheists who insist that even if there is just a one in a trillion chance that a living cell can occur naturally without the involvement of a God, that is sufficient to reject belief in God.

This is an absurd bar since no branch of science could possibly comply with such an expectation. Particle physics, an incredibly demanding field, functions perfectly well with just a 1-in-1.7 million chance that something is not real. This is nearly a million times more forgiving than these atheistic demands on the theist.

At some point, sanity and integrity need to occur in the atheist vs. theist debate. Science has gotten away with innumerable published and peer-reviewed studies using a measly two-sigma, where conclusions are drawn from less than 23 test subjects.

If a subject matter expert with nearly 70,000 hours of experience on the subject states he or she has no idea how the subject in question can come into existence from random chance without the involvement of an intelligence and estimates it to be a four-sigma probability, that is a conservative belief, which, incidentally, is vastly higher than the majority of studies that lie at the foundation of our modern science.

3. More Knowledge Is Always a Good Thing

Increased scientific knowledge has transformed our world and species for the better. While atheism has gained credibility by providing natural explanations for what was previously believed to be evidence of the supernatural (the ever-shrinking “God of the gaps”), the same increase in knowledge has also helped theists justify belief in God using information that was not available in previous centuries (the rising tide of scientific knowledge lifts all boats – not just the atheist ones).

Figure 3: Logical Methodology for Theistic Claims (Image Credit: Edward K. Watson, PJ Media)


If more knowledge on a subject results in a greater likelihood that the subject came into existence from a non-natural cause, anyone who rejects the conclusion is a “denialist” – someone who rejects credible evidence in favor of his or her bias.

When we look at a car or a computer, we can honestly say that it will take an infinitely long period of time for these objects to spontaneously come into existence on their own without the involvement of an intelligence. We can say this because we know how to build cars and computers from scratch. Only those completely ignorant would claim they can emerge out of raw materials by random “luck.”

By way of comparison, when we look at the simplest living cell, with its unimaginably intricate network of complex molecules, the experts on creating complex molecules from simpler ones, the synthetic chemists (not biologists, geneticists, or physicists), have no idea how a cell’s components (amino acids, nucleotides, saccharides, and lipids), much less a living, self-replicating cell, can self-assemble naturally. And this problem gets worse, the more experienced and knowledgeable synthetic chemists become.

What this means is that it is not an argument from ignorance or incredulity (argumentum ad ignorantiam) to use a living cell as an example of probable evidence of God because this is an instance where “more knowledge = less understanding” of how it can arise naturally without the aid of an intelligence.

Figure 4: Logical Process to Determine if Something Likely Has a Natural or Supernatural Origin (Image Credit: Edward K. Watson, PJ Media)

4. Proving a Negative

It is not strictly correct to claim it is impossible to prove a negative because if I were hold up a box to you and say, “There is no candy in this box,” you can determine the truthfulness of the statement by simply looking in it. If there isn’t any candy, you’ve just proven a negative.

The problem with proving a negative is it requires complete knowledge of the conditions for the negative. If the parameters are small (say, within a small box that can be opened), then it isn’t much of a problem. But if it is large (such as the world or the universe), then it becomes impossible to prove because no one can possibly know every detail within every cubic inch of the world or universe.

This is why the default response to any negative statement (“There is no gold in the mine”) isn’t agreement, but skepticism. (“How do you know?”) Follow-up questions could be, “What evidence do you have?” “Have you examined every cubic inch of the land parcel for confirmation?” or, “Have you verified it is not present even in minuscule or non-economical quantities?” After all, the presence of a single gold atom would be sufficient to disprove the expansive negative assertion.

Figure 5: Valid and Invalid Negative Arguments (Image Credit: Edward K. Watson, PJ Media)


Proving God’s reality (“God exists” or “God is real”) requires convincing evidence:

  1. Within the boundaries of where God is supposed to exist such as the world or universe, or
  2. Within areas that support belief in God that are within dimensions that allows one to have complete knowledge of the subject

Both require complete knowledge, but the former is impossible without him actually appearing, while the latter is certainly possible, just like one does not need to observe mosquitos if one has supporting evidence for their existence – such as itchy bites, WNV, dengue, and malaria.

5.  Subjects for Discussion

I’ve observed a lot of strawman arguments against belief in God. They sounded impressive to the layman but were actually empty spectacles that didn’t prove what the atheist was alleging to accomplish.

I am aware of five valid issues that need resolution to determine if there is or isn’t a God:

  1. How did modern humans come into existence?
  2. How did life come into existence?
  3. How did the universe come into existence?
  4. How did the New Testament’s “Gospel” have a single, coherent cosmology without using a common editor and write within a common frame?
  5. If there’s an all-powerful, all-knowing, all-good God, why is there moral evil, physical evil, and undeserved suffering?

Numbers 1 through 4 are empirical issues with the possible causes as:

  1. Nothing supernatural caused them to exist; they just came into existence by chance
  2. God
  3. An alien or aliens

Number 5 is a deductive subject about the problem of evil and outside the scope of this article (since it can only be used with certain “God models”).

Any dialogue must stay within the first four empirical issues because they are not “God of the gap” issues. They are areas where the more one knows, the less likely they appear to originate from random chance.

6. Quantification and Valuation

Another problem that needs to be addressed is quantification and valuation. Proof of God does not fall into easily manageable categories. It’s not like we can use a database containing identical data sets to provide normal distribution analytics with standard deviation. How exactly are we to quantify and assign values to specific items within each empirical issue?

Since the average theist and atheist cannot use standardized probability values towards any component that validates the hypothesis of God as cause, both will then need to agree on an item and its value mutually.

For example, both will need to agree that a living cell membrane’s complexity is a 4σ probability of God if the membrane can’t be replicated naturally using the materials and conditions of a prebiotic earth. Both need to concur that a cell’s polysaccharide glycol’s staggering complexity (six repeat units of the saccharide D-pyranose can form more than one trillion different hexasaccharides through constitutional branching and stereochemical glycosidic diversity) is a 2σ probability if it can’t be replicated naturally. Both need to agree that the likelihood that the correct composition of lipid bilayers surrounding the different subcellular organelles (e.g., the nuclei and mitochondria) perfectly matching is also a 2σ probability if it cannot be formed without the influence of an intelligence.

And these are just three of the dozens, perhaps hundreds of unique items relating to the amazing living cell.

But what if the atheist and theist do not agree on the same probability value? Then no consensus is possible. They will just have to agree to disagree, but it will not be honest for the atheist to claim the theist can’t provide evidence for belief in God provided the theist furnishes reasonable probability values.

Going back to the axiom, Insufficient evidence = No belief; Sufficient evidence = Belief:

At what point will it be fair and honest to say, for example, that the cell’s complexity is sufficient evidence for the existence of God? Should the atheist demand a standard higher or lower than what particle physicists require for their own work?

7. Invalid Atheist Arguments

Smart atheists will avoid giving examples of what they claim prove the nonexistence of God and will put the onus on the believer by using the “Russell’s teapot” argument – the burden of proof is always on those making unverifiable claims. However, New Atheism proponents have overextended themselves by claiming positive arguments against God’s existence.

For any positive argument to appear credible, the atheist must first frame what the positive argument is against. God needs to be “X” for positive argument “1” to disprove. God needs to be “Y” for positive argument “2” to work. The problem is, who told the atheist that “God,” if he exists, needs to be “X” or “Y”? What if he’s actually “C” or “JKL”?

This is why it does not matter what the positive argument is because scientific fact is constantly evolving. What was established fact in 1650 wasn’t in 1790, and what was in 1790 was utterly demolished in 1852, which in turn was proven completely wrong in 1923, which was later supplanted in 2009.

No botanist today will rely on 18th-century concepts. No chemist will use 17th-century textbooks. No doctor will use Galen to practice medicine.

During each of these periods, there were leading scientific experts and those who claimed to be rational thinkers who used the prevailing scientific “facts” as proof God’s not real. And yet, the current experts in those specific fields know and can prove that those earlier “facts” weren’t facts at all, but were misunderstandings of reality.

What this means is that history proves without a doubt that ALL those who rejected God using the scientific proof of their times used faulty evidence.

In other words:

The arguments they used against God are no more credible today than if they claimed proof that God doesn’t exist is because it rained on their birthday!

It is intellectually lazy and morally dishonest to assert that any current scientific claim disproves God and Jesus Christ’s existence because every time anyone has claimed science disproves God in the past three centuries, that person has utilized flawed arguments.

While there’s no doubt we know more about reality than all of our ancestors, the temptation is there to assert, just as our predecessors did, that science proves God isn’t real. However, based on historical evidence, how likely will the scientific “facts” of 2017 be proven correct in the year 2117 or 2217 in any field?

It does not matter how credible we think they are or how utterly convinced we are that this time, it’ll be different. Turing, Freud, Pavlov, Pauling, Monod, Rand, and others who rejected the notion of God used scientific “facts” to justify their unbelief, but these “facts” have now been obsoleted by new viewpoints or are in danger of being replaced.

History shows it’s virtually certain that not one alleged scientific proof of 2017 that “disproves” God’s existence will be proven to be correct a hundred or two hundred years from now. Our skeptical atheistic descendants will be using different arguments that obsoleted the 2017 versions.

Atheists who use positive arguments when arguing against the reality of God inevitably frame erroneous conditions for the argument.

A simple, “How do you know God needs to be like that?” or, “How do you know X means there’s no God?” exposes the straw man.

8. Invalid Theist Arguments

To be fair, theists have been much guiltier of using erroneous arguments because the rules of logic, by their nature, tilt in favor of the skeptic:

Being a skeptic is easy because one does not need to know anything about the rules of logic. Just say, “I don’t believe. Persuade me!” whereas the believer needs to provide evidence that does not fall into a logical fallacy and be sufficiently conclusive to the skeptic—who remains free to accept the evidence or say it’s not convincing enough.

During a debate, a typical theist usually does not start the dialogue by demanding an atheist prove God is not real. The theist starts the debate by providing examples he or she believes prove God is real.

A representative sample of invalid theistic arguments that non-experts use are:

  • God is real because:
    • The Bible says so, OR
    • Jesus rose from the dead, OR
    • The existence of the world is proof God is real, OR
    • The eye is an irreducible complexity, OR
    • I experienced a miracle, OR
    • He answered my prayer

While I believe God exists and Jesus is truly his Son who rose from the dead and the only way for us to be saved, framing the arguments in this manner results in:

  • Logical fallacies (belief in the Bible and Resurrection are not proof of God, given the Bible’s historical transmission and absence of independently-verifiable external evidence of the Resurrection)
  • Faulty evidence (science has several hypotheses of the earth’s creation that appear plausible given what is currently known, and the eye’s current function is not necessarily the same as the earliest evolutionary forms where the mere detection of the difference between darkness and light would’ve conferred an evolutionary advantage)
  • Non-falsifiable, non-predictable, and non-repeatable evidence (there’s no way for someone to disprove that God gave someone a miracle or answered their prayer or predict when someone will receive such a blessing or repeat the process with an identical result)

When these are pointed out, the theist may be tempted to respond to the skeptic with something along the lines of:

“Prove God does not exist.”

And that is the problem because the burden of proof is not on the skeptic. He or she is under no obligation to provide evidence that God does not exist because that would require perfect knowledge of every cubic inch of the entire universe to make sure God isn’t present somewhere in this vast cosmos.

This shifting of the burden of proof when incapable of providing credible evidence is the logical fallacy of “proving the negative.” Anyone who practices it in reference to a volume of space that is larger than what can be known automatically loses the debate.

The only way to avoid this logical fallacy would be to clearly delineate a reasonable boundary where the skeptic is asked to examine where he or she can have complete knowledge (such as within a small box, or within a space smaller than a living cell).

9. Valid Theist Argument

Because the reality or unreality of God is at the world and universe level, and no one can possibly have intimate knowledge of every cubic inch of the world, much less the universe; all evidence of negative or positive statements concerning God will depend on associated evidence that can be independently verified. For example:

These are valid arguments because they support the positive claim (God is real) with empirical evidence in areas where the more one knows, the less likely they appear to be natural in origin (they are not arguments from ignorance or incredulity). And not just one, but four pieces of evidence!

Because they are empirical, they are falsifiable—they can be proven false. They are also predictable—the experimenters can provide specific predictions of what will happen and see if the results matched the hypothesis. They are also repeatable—they can redo the experiment to confirm the results are consistently repeatable.

Skeptics will need to follow the scientific process to confirm:

  • Synthetic chemists can actually try to replicate abiogenesis within a prebiotic earth environment and show how it can occur naturally.
  • Geneticists can actually try replicating the specific mutating combinations that diverged humans from our hominid ancestors that gave us technological intelligence and show how it can occur naturally.
  • Cosmologists and experimental physicists can actually try creating a universe in a lab and show how it can occur naturally.
  • Anyone can ask people to draw parts of a picture on paper of random sizes and put the results together to see if they make a single, coherent image without the involvement of a common editor to harmonize the pieces or common frame to provide instructions to the participants.

What a skeptic cannot honestly do is dismiss the evidence with a wave of his or her hand, because these are empirical issues, with three of them in tiny spaces—the size of the simplest living cell and below. We can prove life exists; we can prove we exist; we can prove that the universe exists; we can prove the New Testament has a single cosmology despite being written by at least nine authors over a period of fifty years.

Consequently, the atheist does not need to have perfect knowledge of every cubic inch of the universe; he or she merely needs to focus on objects the size of the simplest living cell and below, using modern tools and equipment—something that occurs in tens of thousands of labs every day.

The burden of proof is now legitimately moved onto the atheist, who now needs to demonstrate how each of these issues can come into existence by chance without the involvement of an intelligence.


Figure 6: The Right and Wrong Responses to Atheist Challenge (Image Credit: Edward K. Watson, PJ Media)


This provision of empirical support is why it is not possible to equate the alleged existence of God with the alleged existence of Carl Sagan’s dragon, flying spaghetti monsters, teapots in space, Cthulhu, fairies, or bigfoot. We can provide evidence for God’s existence; we can’t for the others.

As Sesame Street would say:

“One of these things is not like the other.”

The atheist will need to rely on subject matter experts in the appropriate fields to provide evidence contrary to theistic claims that have a higher probability of being correct.


Defining dialogue parameters avoids problems and allows proper communication to take place. It also deflates any claim by either party that the opponent is unwilling or incapable of engaging in an honest exchange of ideas.

I will provide detailed arguments in a subsequent article that I believe demonstrate theism is much more credible than atheism, given what we actually “know” as a species.

Note: This article is derived from this author’s upcoming book, Is Jesus “God”?

Editor’s note: The opening sentence of an earlier version of this article read: “Atheism, the rejection of the possibility that “God” exists, has become the dominant thought amongst intellectuals in the past century and has been around longer than most people think.”