Does God exist? My opening speech in debate with William Lane Craig

This is my opening speech in my debate on Tuesday with William Lane Craig. Video above, transcript below. We’ll have video of the full debate online later today.


I’d like to welcome Bill to Ireland. He is a sincere advocate for his beliefs. A week ago I debated an equally sincere Hamza Tzortzis, whose path to Islam was very like Bill’s path to Christianity.

They were both in school at the time. They both had an experience of faith, after a conversation with a classmate. And they each committed their lives to spreading the word of God and Allah respectively.

Both Bill and Hamza know that their Gods exist because of faith. They are both using reason to help to lead people to a personal truth that they know by faith. They are both good, sincere people. And at least one of them if not both are mistaken.

Do Gods exist?

I strongly believe there are no Gods. So I am a strong atheist. I also don’t claim to be able to know that there are no Gods. So I am also an agnostic.

I am always happy to say, even on the question of whether there is a God, that I might be mistaken. But at the moment, I am as confident that the Christian God does not exist as Christians are that Thor does not exist.

‘Does God Exist?’ is not merely a technical claim about how the universe came to be. It is also a claim about having moral authority to tell people how to live their lives. That puts a strong responsibility, and a strong onus of proof, on those making the claim.

Essentially we are talking today about whether the Christian God exists. Because for any other God, Bill and I will simply both agree that they do not exist. Our only area of difference is whether the Christian God exists.

What is most likely to be true?

So how do we evaluate what is most likely to be true?

I suggest that faith and personal experience are the worst and least reliable ways of identifying what is true. They result in different people coming to different beliefs about the same reality.

Applying reason to evidence is the most reliable way. Because it can more reliably result in different people coming to the same beliefs about the same reality.

When we apply reason to evidence, we notice that the idea of a God seems to be implausible, that reality and morality seem as we would expect them to be if there was no God, and that there is a relentless pattern of natural explanations replacing supernatural explanations.

1. The idea of a God seems implausible

Christians typically believe that their God is a pure mind without a body, perfect and changeless, a first cause beyond time and space, all knowing, all powerful and all good. Here are twenty reasons why this idea is implausible.

A Pure Mind without a Body?

1. A pure mind without a body is an invented convenience, because we have no evidence that a mind can exist without a body or a brain or a source of energy. And we have a lot of evidence to suggest that it can’t.

2. Even if we explore this invented convenience, a pure mind without a body might be aware of the existence of matter, but it could not interact with that matter, because there would be no mechanism for it to do so.

Perfect and Changeless?

3. If this God is changeless, then it cannot create anything, because it would have to change in order to do so.

4. Even if you believe it simply willed matter into existence, which is another invented convenience, then that act of will would be a change, within that supposedly changeless mind.

5. But if this mind is perfect, then it could not change anyway, because it would either become more perfect, which is impossible, or less perfect, and thus no longer perfect.

6. Even if it could change, it would not want to change, because, being perfect, it would have no need or desire to do anything.

7. If you respond that it was changeless, but it changed when it created the universe, then it is simply false to say that it is changeless. Or could it change back to being changeless? How would that change happen?

A First Cause Beyond Time and Space?

8. If this God is beyond time, then it cannot cause anything to happen, because cause and effect (if they exist) involve time.

9. If this God created, and interacts with, a universe that involves time and space, then the God is not beyond time and space.

10. If the God is no longer changeless, or beyond time and space, then it may have ceased to exist sometime in the last 14 billion years.

All Perfect, All Knowing, All Powerful and All Good?

11. If this God is all perfect and all good, then it would have created a perfect universe. At a minimum, a perfect universe would not contain suffering or evil.

12. If you respond that even a perfect God can only do what is logically possible, then it is logically possible to have a universe without suffering or evil.

13. If you respond that the universe is actually perfect, but we just don’t understand how, then why would the God have to intervene in this perfect universe through miracles?

14. The Euthyphro dilemma remains: does the God command things to be good for arbitrary reasons, or does it identify things as being good because they correspond to independent standards of goodness?

15. If you respond that the God’s Nature is to be good, and that gets you off, it doesn’t. The dilemma still remains: is the God’s Nature good for arbitrary reasons, or is it good because it corresponds to independent standards of goodness?

16. All of the arguments for an all-good God can just as easily support the idea of an all-evil God, that allows free will so that we can voluntarily choose to be evil, instead of being forced to be evil.

17. If this God is all knowing, then it knows the taste of strawberry yoghurt. But if the God has no body and therefore no senses, how can it know the taste of anything?

18. If you respond that the God only knows the truth of propositions, then the God is not all-knowing. It is less than all-knowing.

19. If this God is all knowing, then it knows what we are going to do in the future. But if it knows that, then either we do not have free will, or else the God has consciously created free agents that it knows will do evil.

20. If this God cares about the lives of humans on planet Earth, then, at a minimum, it could have given us all the same information and the same moral messages.


Finally, let me remind you that all of this is just exploring an invented convenience, which is that there is such a thing as a pure mind without a body. You have to justify that original invention before moving on to its supposed attributes. And you have to justify it in the actual world of reality, not just in the invented universe of discourse of theology.

2. Reality looks like we would expect with no God

The second set of arguments that I want to make is that reality looks like we would expect with no God. Here are ten reasons why.

Created for a Purpose?

1. Theists believe this God created the universe out of nothing. But the modern study of physics is based on patterns, not causes. And it only allows us to examine back as far as the Big Bang. We simply don’t know what might have happened before that. Our universe, or any number of others, might have begun or might be eternal.

2. Theists believe this God created the universe with a purpose. But we do not see the universe moving towards any purpose. Instead, we mostly see impersonal forces pulling and pushing particles around, and mostly moving towards a state of increasing disorder.

3. Theists believe this God fine tuned the physical constants of the universe to allow life. But while these constants do allow life, they don’t seem to be related to that or any purpose.

4. In any case, from a theistic view, life is nothing to do with physical constants. It is spiritual. It could exist alongside any set of physical constants, or even without any physical matter at all. The whole point of theism is that our life is not bound to our physical bodies or physical constants, but is spiritual in nature.

5. Indeed, if you believe that this God is a pure bodiless mind, and if you also believe that matter cannot come from nothing, then the most rational theistic conclusion would be that the God has spawned other pure bodiless minds, and that matter itself is an illusion.

Designed for Humans?

6. Theists believe this God has a special relationship with human beings on planet Earth. But we see a universe that is incredibly wasteful for such an imagined purpose. If it exists, this human-focused God has wasted almost all of time and space in its human focused plan.

(a) Our observable universe is 92 billion light years in diameter, and expanding. It has over 100 billion galaxies, each with 100 billion stars like our Sun. We don’t know how far our Universe extends beyond the observable region. We don’t know whether it is spatially finite or infinite; or if other Universes exist, that exist completely outside it.

(b) Our observable universe is 13.7 billion years old. Life on earth began about 3.8 billion years ago. Human life began about 200 thousand years ago. The Abrahamic God supposedly revealed itself only 4,000 years ago. That’s 4,000 years out of 14 billion years.

(c) For context, the Astronomer Royal Sir Martin Rees once compared the lifespan of our Sun to a human being walking across America from New York to California. He said that on that scale, all of recorded human history would be four or five steps in the middle of Kansas, which, as Professor Rees put it, is hardly the apex of the journey.

7. Theists believe this God created human life as more special than other life. But we know that we are just one evolved species among many. There have been 5 billion species on Earth. 99% of them are extinct. Humans are one of the remaining 50 million species that currently share this tiny planet.

8. We cannot live outside of the planet without the aid of technology. On the planet, we can only live on a small part of the planet’s surface. The part that we can live on has earthquakes and volcanoes and tsunamis. We can die within seconds of being deprived of oxygen, or for any number of other reasons. We can believe things, and do things, that are counterproductive to our survival. Those of us who do the fewest counterproductive things are the ones who survive.

9. We have, however, evolved a capacity to apply reason to evidence. This enables us to understand more about how the universe operates naturally. We can design models of reality, to help us to understand how actual reality works. This provides us with fantastically reliable predictions about reality, particularly when contrasted with the utter unreliability of theistic beliefs. This is enabling us to gradually move beyond earlier beliefs about supernatural agency.

10. Whatever the specific mechanisms that might be involved, human life is as we would expect based on natural evolution. Not as the design of a human-focused God. Yet with astounding self-importance and grandiosity, many humans still believe that we, alone on our planet, alone in our galaxy, and alone in the universe, are the only living beings with God-given immortal souls.

3. Morality looks like we would expect with no God

The third set of arguments that I want to make is that morality also looks like we would expect with no God. Again, here are ten reasons why.

What is morality?

1. Firstly, what do I mean by morality? An outcome is objectively bad if it harms a sentient being. An action is objectively wrong if the agent unjustly harms a sentient being. In any given situation, it can be easy or hard to know what is right and wrong.

2. If there was an all-knowing, all perfect, all good God that is the source of morality and cares about human beings on planet Earth, then at a minimum, we would expect it to be able to give us all the same moral message, and we would see throughout different parts of the world and different times in history that people would have the same sense of morality. But this not what we see.

3. If there is no God, then we would expect to see is that different sets of people at different times and different places in the world would be evolving different ideas and codes of morality. And this is indeed what we do see.

4. In parallel to applying reason to the evidence of reality, in order to try to understand what is objectively true about reality, we can also apply reason to the evidence of our behaviour, in order to try to understand what is objectively true about morality.

5. It is simply false to suggest that we need a God to assist us in doing this. There are many approaches to moral philosophy that do not invoke Gods.

How did morality evolve?

6. Here is one plausible model.

(a) Morality has evolved in the brains of social animals, including humans, because both cooperation and competition help us to survive.

(b) When parents look after their children, their children are more likely to grow up. When a tribe cooperates in gathering food, the tribe is more likely to survive. So genes for caring for children, and genes for cooperating, tend to be passed on from generation to generation, and become more common.

(c) We see three phases of evolving morality among social animals. The first phase is empathy and compassion. The second phase is cooperation and reciprocity. The third phase is understanding fairness and justice

(d) Many nonhuman animals exhibit these types of morality. In one experiment, rats would refuse food if they saw another rat being electrocuted. Which says a lot about human morality, setting up an experiment like that. In another experiment, monkeys were given food if they put a token into a slot. Some monkeys couldn’t figure it out. Another monkey would take that monkey’s token, put it in the slot, and let the first monkey have the food.

(e) But aside from that, humans and some other animals have a greater capacity for more nuanced morality, because we have a greater capacity for reason. We can know that something is wrong, because we can understand that it causes unjustified harm.

(f) So our sentience and consciousness and our ability to reason therefore give us a special role in sharing our lives on this tiny planet while we are alive, in that our behaviour has consequences for other living beings. But that does not extend to us having a special place in the overall universe

Morality without belief in God?

7. I subscribe to a variation of John Rawls social contract theory of morality. Essentially, that is:

(a) How would a perfectly rational set of people design principles of justice for a society, if we don’t know in advance what position we would hold in that society? That is, we don’t know if we will be rich or poor, male or female, healthy or sick. This veil of ignorance forces us to be impartial, and to develop universally just principles.

(b) My personal addition to the theory is that we also should not know what species we would be. I believe one of the greatest injustices in our world is how we treat nonhuman animals. Every year we kill over 50 billion farmed animals, and up to a trillion fish. These sentient beings suffer unjustly for our convenience, and our slaughter of them is an ongoing moral atrocity.

Morality with belief in God?

8. In any given circumstance, it is already hard enough to understand and figure out the best balance between the requirements of empathy, compassion, cooperation, reciprocity, fairness and justice.

9. But religion corrupts this already-difficult process by adding in imagined supposedly supernatural commands that are unrelated to compassion, cooperation or justice.

(a) And so you see Verse 24:2 of the Quran saying: flog adulterers 100 times each, and do not let your compassion stop you. Because clearly some early Muslims knew that this punishment was disproportionate and immoral, and so they had to be specifically told to not let their compassion stop them.

(b) And you see Deuteronomy and 1 Samuel in the Bible, where the Christian God repeatedly commands the Israelites to attack the cities of other tribes, to show them no compassion, and to completely destroy them, putting to death man woman child and infant, and leaving nothing alive that breathes.

And you get otherwise good people like Bill here, who I genuinely respect as a good person, defending this act of slaughter because of his religious belief, on the grounds that it is good because God commanded it, even though it would have been bad if God had not commanded it, including defending the slaughter of infants and children on the basis that they would have gone straight to heaven.

10. Not only is belief in a God not needed for objective morality, but belief in a God can corrupt our rational search for that objective morality. Even in the mind of an obviously good man like Bill.

4. Conclusion

I’ll address Bill’s opening arguments in my next contribution. Bill, I know I’ve given you a lot to respond to here, and I would like you to respond to as much as you can, but while doing so can you please prioritise responding to these questions:

  1. Is it possible that you might be mistaken that the Christian God exists? If so, what evidence would convince you? And I am happy to say that I might be mistaken about my belief.
  2. How do you justify the supposed existence of a pure mind without a body, when there is no evidence that such a thing can exist? And by what mechanism could such a thing create and interact with matter?
  3. Is it logically possible to have a universe without suffering or evil?
  4. Why is God’s nature good? Is it good for arbitrary reasons, or is it good because it corresponds to independent standards of goodness?
  5. How do you justify, as objectively moral, the Christian God repeatedly ordering the Israelites to slaughter children and infants of other tribes?

So to summarise my overview: Is there a God? I don’t know, Bill doesn’t know, none of us knows. So what is the most reliable way of finding out?

I suggest that faith and personal experience are the least reliable ways, because they result in different people coming to different beliefs about the same reality.

Applying reason to evidence is the most reliable way, because it can more reliably result in different people coming to the same beliefs about the same reality.

When we apply reason to evidence, we notice that the idea of a God seems to be implausible, that reality and morality seem as we would expect them to be if there was no God, and that natural explanations are relentlessly replacing supernatural explanations.

And while there are still questions that we don’t yet understand the answers to, I suggest that on the basis of the relentless flow of natural explanations replacing supernatural ones, and nothing going in the opposite direction, it is more reasonable than not, until we get evidence to the contrary, to believe there is no God.

Join the Conversation


  1. Ask a theist this question:

    God comes to you. You know it is your God, there is no possible doubt. Your God says “To properly worship me and be a good and moral person, you must kill and consume a human infant.” What do you say?

    There are three possible responses
    A) “No way.” Congratulations, you have used your own morality to reject God’s morality. This shows that morality is not the sole provenance of a God. This is easy to see in the Bible and Koran as God commands many things that we know are immoral.

    B) “My God would never say or require that.” Great, you have shown that your God is not the font of morality, but beholden to an external morality that does not come from the deity. Indeed, I would submit that the source of morality is YOU.

    C) “Pass the ketchup.” This is the ONLY possible response for a true believer. If they do not say this, then they are not truly willing to follow their God. And, if they do say this, run far, far away from them and alert the authorities.

  2. “And they each committed their lives to spreading the word of God and Allah respectively.”

    This is a disappointingly ignorant statement from michael- which is surprising. The wurd ‘Allah’ is the Arabic wurd for God. Arab Christians use it (and not the English wurd ‘God’!) (‘Alah’ is the wurd in Aramaic btw.) You might as well say, “Each committed their lives to spreding the wurd’v ‘Theos’ and Allah’.

    But why say wun wurd in English / the uthr in Arabic. why not use Dieu or Bog or Tanri or Atnatu or Deus?

    The wurd Allah is, in point’v fact, actually’v judeo – xtian origin


  3. Michael,

    This was a wonderful and concise set of arguments. Thank you for taking the time to present. I am an Christian and a Pastor in Reno, Nevada. I wonder if you might be able to clarify something.

    Early in your speech you said,

    “‘Does God Exist?’ is not merely a technical claim about how the universe came to be. It is also a claim about having moral authority to tell people how to live their lives. That puts a strong responsibility, and a strong onus of proof, on those making the claim.”

    First, I would say that the Christian perspective is not that believers should engage in “telling non-believers how to live their lives.” Our task instead is to invite a non-believer to consider the plausibility and transcendence of the claims of Christ as revealed in the scripture. Only when that person has accepted those claims is he accountable to the life-shaping counsel of the scriptures to which he claims to adhere.

    Can you demonstrate how the lack of belief in the existence of a god somehow avoids any type of moral imperative? To me, the most plausible ethical system for a naturalist or materialist worldview is as you described above is humanism. If materialists ruled a society, surely you wouldn’t expect that there would be no moral authority. Would authorities in that society not be expected to enforce some sort of ethical code?

    It seems that neither worldview can possibly avoid carrying some sort of “moral authority”, and therefore both have an equally strong onus for demonstrating proof.

    Thank you again for an excellent presentation, you’ve given me much to consider!

    From across the ocean, Ryan.

  4. Ryan, I agree that there are moral values independently of belief in gods. I personally don’t call them humanist values, because I also extend moral values to nonhuman animals.

    But those moral values (at least in the sense that I advocate) are based on applying reason to principles such as empathy, compassion, cooperation, reciprocity, fairness and justice. They are not based on claiming divine authority from an unidentifiable supernatural being.

    So natural moral values can be examined and justified or rejected based on reason, while divine command values have to simply be followed even when it is clear that they are unjust.

  5. Therefore it is immoral t kill a fetus, a fish or wurm…sentient beings. Is this whot Craig calls specieism?

    I’v nevr undertood why xtians rubbish humans (sinnrs, depravd) but hav instrinsic valu – being creatid in the imij’v Jesus (whu causes mums and dads t eat thier own childrin eg jer 19.9 – an act which is nesasrily “good” as per his “good” nature).

    but why is justis a good? Is it so arbitrurily?

    But Michael how did u address the is/ought thing? Or this irrelevant?


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