The Byproduct Theory of Religion: Why We Believe in Gods

If there is no god, why do so many people believe in one? What is it about human psychology that has made belief in god, in one form or another, the default position for the majority of human beings? You may be tempted to attribute all religious beliefs to human irrationality, constant social reinforcement, the fear of death, and being relieved of responsibilities like finding meaning or figuring out what’s moral, among other things that we could certainly talk about. And you definitely wouldn’t be wrong to say that, but you’d still be missing a fundamental part of the story — why do the world’s religions have so much in common, why are they so widespread, and why do many religious beliefs seem to come so naturally to us?

The theory of religion as a byproduct provides a potential answer for why we tend towards mystical beliefs in souls, gods, and an afterlife. The idea is that religion, while not necessarily an adaptation itself, is a byproduct of psychological adaptations that we use to navigate the social landscape. These psychological functions evolved for some other purpose, and our mystical and superstitious beliefs result as a byproduct of these mechanisms. So it’s not that religious beliefs are social constructs, or that they’re biologically adaptive, but rather that they’re accidental byproducts caused by misfiring of very powerful cognitive systems that evolved for other reasons. Our psychological evolution imbued us with very helpful cognitive devices like theory of mind, decoupled cognition, and agency detection, all of which we’ll dive into in a minute. These mechanisms can misfire — and as a result, create beliefs in souls, an afterlife, and even god as a byproduct.

Theory of Mind

Theory of Mind is the ability to attribute invisible minds to other people as a way of explaining their behavior. We can’t actually get inside someone’s head, and if you’re a social animal trying to survive and succeed, that’s a problem. We developed Theory of Mind to decipher other people’s intent, thoughts, beliefs, desires, and feelings based on nothing but outward, physical indicators.

As social beings, we have to be able to imagine how someone might react in a given situation, or what that person probably thinks of you. With good accuracy, we can intuit the feelings and intentions of other people by looking at their facial expression and body language. You can actually tell someone’s mental state by seeing that they’re smiling. You can tell that they’re internally, subjectively feeling a certain emotion based on nothing but the weird way that they’re stretching their face. And if they’re fake smiling, you can tell that too, and that tells you something about their subjective mental state. It’s amazing that we have this ability to know, usually automatically, without thinking about it — the inner state of other people based on purely physical indicators.

But since it comes so naturally to us to attribute an imaginary mind to a physical object in front of us, like humans or pets, it’s not so hard to imagine how this could misfire. It’s a short step from that to minds that are detached from bodies, which is all a soul or a spirit is. It’s just this thing that we’re already doing, Theory of Mind, except with no physical body in front of us. It’s a totally normal concept, with one slight modification.

A piece of evidence that supports the Byproduct Theory is that those who are deficient in some of these cognitive functions also tend to be more atheistic. Those with autism, for example, aren’t strong with theory of mind. They have a much more difficult time reading other peoples’ thoughts and emotions. When you’re feeling awkward, a person with autism has a much harder time telling based on your body language and facial expression like someone with good Theory of Mind would. Autistic people are also predisposed to be nonbelievers at much higher rates. If Byproduct Theory is correct, that’s exactly what you would predict. Those who lack the psychological mechanisms that misfire and create religious beliefs, like theory of mind, would be more predisposed to nonbelief — and this is what we see.

Decoupled Cognition

Humans have a remarkable ability to create a complex interaction with an unseen other, called decoupled cognition. We win arguments in the shower with debaters who are only in our own heads, we can mentally rehearse conversations before they happen; we also mentally replay conversations and say different things and we did in real life. We’re able to have emotionally charged interactions with absolutely no one. We have intense debates, make jokes, and have conversations in our own heads without even trying to. This is what’s called decoupled cognition. We can imagine someone else’s mind and guess how they would respond without them having to be right in front of us. It would be difficult to take advantage of our Theory of Mind to it’s full extent if a person always had to be physically sitting right in front of you in order for you to have an interaction with them. Our social lives would be seriously hobbled without decoupled cognition. It allows us to travel through time, location, and circumstance and plan how we’ll manage ourselves in any situation, and fine-tune our behavior by ruminating on past conversations and engaging in possible future scenarios.

There’s a large faction of Christian believers for whom prayer is an interactive experience. When they say they talk to God, they mean just that — they have conversations with God in their head. Decoupled Cognition and Theory of Mind, which both evolved for their adaptive social benefits, easily lend themselves to this experience of having a personal relationship with God. As many believers do, you can literally have a conversation with God using these psychological mechanisms that come very naturally to us.


Substance dualism, the idea that our minds and bodies are made of two entirely different substances, seems to come naturally to us. As Paul Bloom says, we are “natural-born dualists”. Intuitively, on a gut level, we feel that our minds are separate from our bodies. Our common sense dualism isn’t rooted in great philosophical arguments and empirical evidence, rather, it’s rooted in our subjective experience. I don’t feel like a body, I feel like I have a body. I don’t feel like a brain; I feel like I’m a mind inhabiting a body. The fact that dualism is the common sense, intuitive view is due to our felt experience of being separate entities riding around behind our eyes. Even neuroscientists slip into dualistic language sometimes, saying things like, ”I think about sex and that activates this part of my brain”—as if the thought came first, before the brain activity.  And the fact that dualism is the intuitive view doesn’t count as evidence in favor of it — our common sense also tells us that heavier objects would fall faster than lighter objects when dropped.

Our intuitive dualism lends itself easily to many religious ideas. The idea of an afterlife where your mind leaves your body after death and goes to heaven or hell wouldn’t be possible if not for dualism. The idea of ghosts and souls wouldn’t be possible at all without dualism, and neither would the idea of God, who’s supposed to be a disembodied mind, made of purely mental substance. The main point is that our felt experience of dualism allows for us to imagine souls, an afterlife, and a god quite easily, without ever being counterintuitive.

Agenticity, or Hyperactive Agency Detection

In his book Why would anyone believe in God?, Justin Barrett suggests that the brain has a mental module he calls our Hyperactive Agency Detection Device, which probably exists to identify danger. This module has a survival benefit even if it is over-sensitive — it’s better to avoid an imaginary predator than to not notice a real one. Michael Shermer coined the word agenticity to describe our tendency to detect agents, even when there are none. Our tendency to favor agent causation over causation from impersonal forces is safer, so there’s selective pressure favoring hyperactive agency detection. We’re all descended from those who tend towards false positives rather than false negatives when it comes to agent detection. As a result, we are strongly biased to interpret unclear events as being caused by a conscious agent, rather than by impersonal causes. When you hear a noise in the middle of the night, your brain jumps straight to “Robber!” or even “Ghost!” before considering anything else. If you’ve ever had a dog, you may have noticed him doing the same thing as well, because the same selection favoring agenticity acted on his species. The specific agent you think you see isn’t important. The point is that we have a propensity to see agents — conscious beings with intentions — where there aren’t any.

It’s a short step from dualism, Theory of Mind, and Hyperactive Agency Detection for it to be possible to see God everywhere all the time. You see God working when anything good happens, like a remission of cancer or a good parking space opening up. Think of all the adults who believe in Karma in one form or another, or that everything happens for a reason. Our ancestors believed that gods caused earthquakes, volcanic eruptions, and diseases, often in response to human action. They believed that a conscious agent was causing these things as a result of human behavior. Even today, people believe things like “Hurricane Katrina hit New Orleans because of witchcraft,” or “9/11 happened because of homosexuality and abortion,” or “Christopher Hitchens got cancer because he was an atheist.” (Some significant number of Christians have claimed all of these things).

It comes very naturally to us to attribute minds to blobs of matter in front of us, like we do with humans every day using Theory of Mind. We do this in order to explain people’s behavior — we figure out what their inner mental state is based on nothing but outward signals. It may seem counterintuitive at first, but it’s a short step from intuiting someone’s intentions using Theory of Mind, to claiming as Jerry Falwell and Pat Robertson did, that 9/11 was God’s punishment for gays, abortion, feminists, and the ACLU. They think that God, a disembodied mind, allowed this to happen, and he’s trying to figure out God’s inner mental state based on the outward physical signs.

In the story of Jonah and the whale, the ship’s crew thinks the terrible storm is the result of a god’s bad mood. The logic of this is not even questioned in the story, and it’s assumed that the reader will think this is common sense. In fact, in the story, the crew was proven right! The bad weather was the result of an agent — a conscious mind who was communicating his anger through a natural disaster. This is, among other things, an example of Theory of Mind, dualism, and Hyperactive Agency Detection at work.

There’s a lot more to Byproduct Theory than what I’ve laid out, but the basic idea is this: religious beliefs are accidental byproducts of biological systems that evolved for other reasons. It’s not that religions are social constructs, or that they’re biological adaptations in and of themselves, but that they’re unpredicted byproducts of very powerful social and cognitive systems that evolved separately. I think this question of why people believe in gods is an important question that we should feel some burden to answer. Of course, no theistic arguments are validated if we’re unable to come up with a naturalistic explanation for religion. We didn’t need to have a perfect theory of the shape of the earth to know that the earth wasn’t flat. Logically, we don’t need a naturalistic theory, but psychologically, I think we do need an answer. When it comes to understanding religion as a natural phenomenon, the theory of religion as a byproduct is not the only game in town, and it’s not mutually incompatible with every other idea that’s on the table, but I think it’s easily the most compelling. I think it’s possible and even highly likely that religion was an accident.


I relied heavily on the book Why We Believe in God(s) by J. Anderson Thomson and Clare Aukofer for this episode; the link is the show notes, along with my other resources if you’d like to learn more about the theory of religion as a byproduct.

J. Anderson Thomson – American Atheists Lecture [YouTube]

Why We Believe in God(s) – J. Anderson Thomson [Amazon]

Steven Pinker on Byproduct Theory [YouTube]

Michael Shermer on Belief [YouTube]

Paul Bloom on Byproduct Theory [YouTube]

Paul Bloom on Dualism []

Why Would Anyone Believe in God? – Justin Barrett [Amazon]

The Believing Brain – Michael Shermer [Amazon]

Religion Explained: The Evolutionary Origins of Religious Thought – Pascal Boyer [Amazon]

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