An atheist is someone who does not believe that any god exists. An agnostic is someone who holds that whether a god exists is unknown, or cannot be known at all. Atheism answers a question about belief, while agnosticism answers a question about knowledge. Because the two words answer different questions, a person can be both at once, and many people describe themselves exactly that way.
Agnostic vs Atheist at a Glance
| Atheist | Agnostic | |
|---|---|---|
| Question it answers | Do you believe a god exists? | Can anyone know whether a god exists? |
| Core position | Does not hold a belief in any god (or, in the stronger sense, holds that no god exists) | Holds that the answer is unknown, or cannot be known |
| About | Belief | Knowledge |
| Can you be both? | Yes, in everyday usage: an “agnostic atheist” lacks belief and does not claim certainty | |
| Origin of the word | From the Greek atheos, “without god” | Coined by the biologist T. H. Huxley in the nineteenth century |
The rest of this guide explains each term, sets out the two different ways the words are used, and shows where the labels came from and how many people use them today.
Clear Definitions of Each Term
Four words do most of the work in this discussion, and they pair up into two simple sets: one about belief and one about knowledge.
- Theist: a person who believes at least one god exists.
- Atheist: a person who does not hold that belief. The prefix a means “without”, so an atheist is, quite literally, someone without theism. In its broad sense the word describes an absence of belief rather than a claim that gods are impossible.
- Gnostic: in this narrow philosophical sense, a person who claims to know whether a god exists. The root is the Greek gnosis, meaning knowledge.
- Agnostic: a person who holds that this knowledge is not available, either to them personally or to anyone at all.
Theist and atheist describe belief. Gnostic and agnostic describe knowledge. Keeping those two pairs apart removes most of the confusion between the terms.
Two Ways the Words Are Used
Much of the disagreement about these labels comes from the fact that they are used in two different ways, and both are legitimate. Knowing which sense someone means usually settles the argument.
The everyday sense: belief and knowledge as separate questions
In everyday conversation, and among most people who call themselves atheists, atheism means simply not believing in any god. On this reading, agnosticism is not a middle position between belief and unbelief. It is an answer to a different question, about what can be known, so everyone has both a belief answer and a knowledge answer. This is the usage behind the four combinations described further down, and behind the common label “agnostic atheist”.
The philosophical sense: three answers to one question
Academic philosophy usually draws the lines differently. The Stanford Encyclopedia of Philosophy notes that in philosophy the word atheism is standardly used for the proposition that God does not exist, not for a lack of belief. On that usage there are three positions on a single question: the theist affirms that God exists, the atheist denies it, and the agnostic suspends judgement. Here agnosticism really is a middle position, and an agnostic is neither a theist nor an atheist. The encyclopedia accepts that the broader, lack-of-belief sense is a legitimate usage too, but it prefers the narrower sense for philosophical work, because only a proposition can be true or false and argued for.
Neither usage is a mistake. When two people seem to disagree about whether agnostics are atheists, they are very often using these two different senses without realising it.
Where the Word Agnostic Came From
The word atheist is ancient, but agnostic is a Victorian invention. The English biologist Thomas Henry Huxley, a leading defender of Darwin, explained in his 1889 essay Agnosticism that he made the word up while a member of the Metaphysical Society, a London debating club founded in 1869. He wanted a label for his own position, and he described how he chose it:
“It came into my head as suggestively antithetic to the ‘gnostic’ of Church history, who professed to know so much about the very things of which I was ignorant.”
T. H. Huxley, Agnosticism (1889)
For Huxley, agnosticism was not a belief about God at all. In the same essay he wrote that “agnosticism, in fact, is not a creed, but a method”, and he summed up that method in a single principle:
“In matters of the intellect, follow your reason as far as it will take you, without regard to any other consideration. And negatively: In matters of the intellect do not pretend that conclusions are certain which are not demonstrated or demonstrable.”
T. H. Huxley, Agnosticism (1889)
That original meaning, a refusal to claim certainty beyond the evidence, is still the core of the word today, whichever of the two usages above a person prefers.
The Four Combinations of Belief and Knowledge
On the everyday usage, the belief question and the knowledge question combine into four positions. Each one describes an outlook that real people hold, and many readers find it the quickest way to place themselves.
Gnostic Theist
This person believes a god exists and claims to know it with certainty. Many devout believers describe their faith in these terms, treating it as settled knowledge rather than an open question.
Agnostic Theist
This person believes in a god but does not claim certainty about it. They hold their belief as trust or faith while accepting that it cannot be proved. Many reflective religious people describe themselves this way.
Gnostic Atheist
This person does not believe in a god and claims to know that none exists. It is sometimes called strong or positive atheism. People who hold it often apply it most firmly to specific, clearly defined gods, and less firmly to vaguer ideas of the divine that are hard to test.
Agnostic Atheist
This person does not believe in a god but does not claim to know for certain that none exists. They find the case for any god unpersuasive and withhold belief on that basis. It is a common position among people who call themselves atheists, and it causes the most confusion, because the two words sound as if they should cancel out. On the everyday usage they do not: one describes knowledge and the other describes belief.
| Position | Believes a god exists? | Claims to know? |
|---|---|---|
| Gnostic theist | Yes | Yes |
| Agnostic theist | Yes | No |
| Agnostic atheist | No | No |
| Gnostic atheist | No | Yes |
The Spectrum of Theistic Probability
The biologist Richard Dawkins proposed a different way to picture the question in his 2006 book The God Delusion. Instead of a yes or no, he described a spectrum of seven points, from complete certainty that God exists to complete certainty that God does not.
- Strong theist: certain that God exists.
- De facto theist: not certain, but believes strongly and lives on that assumption.
- Leaning towards theism: very uncertain, but inclined to believe.
- Completely impartial: regards existence and non-existence as exactly equally likely.
- Leaning towards atheism: does not know, but inclined to be sceptical.
- De facto atheist: thinks God very improbable and lives on the assumption that there is none.
- Strong atheist: certain that there is no God.
Dawkins placed himself at six in the book, and in later interviews he suggested that 6.9 was more accurate. The scale is useful because it treats certainty as a matter of degree. On it, a person who calls themselves an agnostic might sit anywhere from three to five, while most people who call themselves atheists sit at six or seven.
How Many People Are Atheist or Agnostic?
Survey data show that people really do treat the two labels as different. In a Pew Research Center survey of more than 11,000 American adults, carried out in 2023 and published in January 2024, 28% of adults had no religious affiliation. Within that group, 17% described themselves as atheists, 20% as agnostics, and 63% as “nothing in particular”. So among people without a religion, slightly more chose agnostic than atheist, and most chose neither label at all.
The same report found differences between the groups in background and outlook, which is one reason researchers count them separately rather than treating every non-religious person as the same.
Related Terms People Confuse With These
Several neighbouring words come up in the same conversations, and each has its own meaning.
- Deist: someone who believes a god created the universe and then stepped back, taking no further part. A deist is a kind of theist, but one without revelation, scripture or answered prayer.
- Pantheist: someone who identifies god with the universe itself rather than with a separate being. For a pantheist, nature and the divine are the same thing.
- Apatheist: someone who does not care whether a god exists, regarding the question as unimportant to how they live.
- Ignostic: someone who argues that the word “god” is too vaguely defined for the question to mean anything until the term is pinned down.
- Antitheist: someone who not only lacks belief but regards religion as harmful and opposes it. An antitheist is an atheist with a stated objection to religion.
- Freethinker and humanist: broader labels for people who form their views on religion through reason rather than authority, and who often, but not always, are atheists or agnostics.
Which One Am I?
If you are unsure which label fits, two plain questions will usually place you, and the answers are entirely your own.
- Do you believe that a god exists? If yes, you are some kind of theist. If no, or if you simply lack that belief, you are an atheist in the everyday sense of the word.
- Do you claim to know the answer with certainty? If yes, you are gnostic about it. If no, you are agnostic about it.
If you prefer the philosophical usage, the question becomes simpler: do you affirm that God exists, deny it, or suspend judgement? Those answers correspond to theist, atheist and agnostic. Many people use whichever label they feel describes them best, and the choice is a matter of honest self-description rather than a test with a right answer.
Common Misconceptions, Corrected
“Agnostic is always the middle ground between belief and atheism.” That is true on the philosophical usage, where the agnostic suspends judgement. On the everyday usage it is not, because agnosticism answers the knowledge question and leaves the belief question open.
“All atheists claim to know there is no god.” Some do, and in philosophy the word is often used that way. Many people who call themselves atheists, however, mean only that they do not believe in a god, without claiming certainty.
“Agnosticism is a religion.” It is neither a religion nor a faith. It is a position about the limits of knowledge, and it has no rituals, doctrines or congregations.
“One label is more respectable than the other.” Neither is a moral ranking. Both describe where a person stands on belief and knowledge, not their character.
Frequently Asked Questions
What is the main difference between an agnostic and an atheist?
An atheist does not believe in any god, while an agnostic holds that the existence of a god is unknown or unknowable. Atheism concerns belief and agnosticism concerns knowledge.
Can you be both agnostic and atheist?
Yes, on the everyday usage. An agnostic atheist does not believe in a god and does not claim to know for certain that none exists. On the philosophical usage, where atheism means denying that God exists, agnostic and atheist are separate positions instead.
Is agnostic just a softer word for atheist?
The words are not synonyms. Some people choose agnostic because it sounds less confrontational, but the terms describe different things: agnostic describes a view about knowledge, and atheist describes a lack of belief or a denial.
Do agnostics believe in God?
Agnosticism on its own does not settle that. An agnostic theist believes in a god without claiming certainty, while an agnostic atheist does not believe. Someone who uses agnostic in the philosophical sense neither believes nor disbelieves.
Who invented the word agnostic?
The English biologist Thomas Henry Huxley coined it in the late nineteenth century, as a contrast with the “gnostics” of early Church history who claimed special knowledge of God.
What is the difference between gnostic and agnostic?
In this context, gnostic means claiming to know whether a god exists, and agnostic means holding that such knowledge is not available. The pair describes certainty, and it applies to believers and non-believers alike.
Summary
Atheist and agnostic answer different questions. Atheism is about belief: an atheist does not believe in any god, or in the stricter philosophical sense holds that no god exists. Agnosticism is about knowledge: an agnostic holds that whether a god exists is unknown or cannot be known. In everyday usage the two combine, so a person can be an agnostic atheist or an agnostic theist. In philosophy the agnostic is usually the person who suspends judgement between theism and atheism. Knowing which sense is in play resolves most disagreements about the labels.
For more on related questions, you may want to read why atheism is not a religion, what lies behind the decision when people become atheists, and a fuller account of atheism as a definition and a history.
Sources
- T. H. Huxley, “Agnosticism” (1889), Collected Essays, vol. V. Full text, Clark University Huxley archive.
- Paul Draper, “Atheism and Agnosticism”, Stanford Encyclopedia of Philosophy (first published 2017, revised 2022). plato.stanford.edu.
- Richard Dawkins, The God Delusion (London: Bantam Press, 2006), chapter 2.
- Pew Research Center, “Religious ‘Nones’ in America: Who They Are and What They Believe” (24 January 2024). pewresearch.org.
Pingback: The Non-Religious Conservative: What the Secular Right Tells Us About Atheism's Unfinished Work - AtheistWave
This is an excellent write-up. But, I’m confused by your demand for certainty with knowledge. I don’t believe knowledge demands certainty. If it did, all of our scientific knowledge that build the entirety of the modern world could not be called knowledge.
Since we don’t demand certainty for scientific knowledge, why demand certainty for the knowledge of whether god(s) exist? I believe rather than asking “do you claim to know the answer for certain?” you should state the question as “do you claim to know the answer?”
We all know (I hope) that if we drop a bowling ball near the surface of the earth that it will fall down rather than up. But, this cannot be proven with absolute certainty. All we can do is show the overwhelming evidence of having performed this experiment numerous times with the same result.
In fact, if one thinks about this for any length of time, we can only know that the ball will fall down to the same degree of confidence that we say there are no gods. Surely any god worthy of the title would be able to catch the ball and hold it in mid air. Or, a god could cause it to fall up.
tl;dr: I think you should remove the demand for absolute certainty from your definition of gnosticism and just change it to a claim of knowledge without the claim of certainty.