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What Is the Definition of Atheist, Agnostic, and Other Related Terms?

Science, philosophy, politics, and religion are frequent topics for writer and public speaker Catherine Giordano.

What is the difference between atheist and agnostic?.

What is the difference between atheist and agnostic?.

What Is the Definition and Etymology of Atheism?

Atheism simply means no belief in the existence of God or gods. It comes from the Greek word atheos which is a compound word with “a” meaning without and “theos” meaning god or gods. It is the opposite of theism; it is non-theism.

In ancient Greek, the adjective atheos meant "godless." It was a derogatory term used to describe someone who did not worship the gods of the time or who was not sufficiently devout in his worship of these gods. Around the 5th century BCE, the term came to mean the intentional denial of the existence of the gods.

After the introduction of Christianity, both the early Christians and the followers of the Hellenist (Greco-Roman-Egyptian) gods each used the term pejoratively to describe the other. The term was always used as an insult. No one would self-identify as an atheist.

It wasn’t until the late 18th century, in Europe, that the term “atheism“ first started to be used as merely a descriptive term for lack of belief in the monotheistic Abrahamic God. In Western society today, this is how the word “atheism” is most commonly used—it simply means “disbelief in God” (where God refers to the Abrahamic God worshiped by Jews, Christians, and Muslims).

However, in the 20th century, the term “atheism” sometimes took on a more expansive meaning—it began to be used to indicate a disbelief in all deities.

Hence, any discussion about atheism must begin with a mention of which meaning is being used for the word "atheism" as well as for the word "God."

What Is the Definition and Etymology of Agnosticism?

The term “agnostic” was coined in 1870 by the biologist, T.H. Huxley (1825-1895). He took the Greek word “a” which means “without” and the Greek word “gnostos” which means “known” to create the word agnostic which has come to mean “the existence of God is unknown and/or unknowable.” He used the word gnostic as a reference to the word “Gnosticism,” a branch of early Christianity which was eventually declared to be heresy by the Orthodox Church.

Huxley urged us, “Do not pretend that conclusions are certain which are not demonstrated or demonstrable.” He also said, “It is wrong for a man to say he is certain of the objective truth of a proposition unless he can provide evidence which logically justifies that certainty.”

Huxley was a skeptic, but he rejected the label infidel. He stressed that agnosticism was a method for the study of religion and not a creed. He wished to apply the scientific method to the study of the veracity of the New Testament claims about Jesus; he thought a Christian should look at the Bible as a historian looks at history.

For more details about T. H. Huxley's views on agnosticism, see Huxley's Agnosticism

Atheist-Agnostic Chart

There are four ways to combine of atheism/theism and agnosticism/gnosticism.

There are four ways to combine of atheism/theism and agnosticism/gnosticism.

Can Atheism and Agnosticism Be Combined?

There is endless debate in the freethinker community about atheism vs. agnosticism and how the two relate to each other. Some will say atheism refers to what one believes about God and agnosticism refers to what one knows about God.

An agnostic-atheist or (atheistic agnostic) is someone who does not believe that God exists because there is insufficient evidence for the hypothesis that God exists or that the hypothesis that God exists is simply unknowable and can never be proven or disproven.

An agnostic-theist believes that God exists, but he does not know this for a certainty. He may say that the characteristics of God cannot be known or proven.

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There are gnostic versions of atheists and theists. They differ from the above two in that they are 100% certain of the existence or non-existence of God.

These beliefs are sometimes diagramed.

The Dawkins Scale

The Dawkins Scale of goes from strong theist to strong atheist with several intermediate stances.

The Dawkins Scale of goes from strong theist to strong atheist with several intermediate stances.

Personally, I think creating four categories instead of two is just playing semantic games. Everyone is either a theist or an atheist. As Carl Sagan wrote, “Agnostics are atheists who lack the courage of their convictions.”

For instance, an agnostic does not know if God exists or not. How can he say he believes something and at the same time say he doesn’t know if it is true? If he doesn’t know it to be true, he must be an atheist. Does he say he is an agnostic-atheist because he is open to new evidence that might prove the existence of God? Well so is the atheist. I’m an atheist, but if I am presented with credible evidence I will change my mind. Until then, I don’t believe.

The same argument works in reverse for theists. If someone believes, but says he is not sure, how can he claim to be a believer? Perhaps he merely chooses to believe and doesn’t care if his belief is true or not. If he has doubts about his belief, he has placed himself in the non-believer camp until such time as he resolves those doubts.

I will leave the gnostic and agnostic qualifiers to philosophers and speak the way ordinary people speak in ordinary conversation.

Sometimes, people use The Dawkins Scale to assign their degree of belief and non-belief. It is taken from the book The God Delusion written by scientist (evolutionary biologist) Richard Dawkins.

I like this scale because it puts "agnostic" in the middle, and defines it as someone who literally thinks that there is a 50/50 chance that God exists or does not exist. It requires everyone else to pick a side--either atheist or a theist-- even if they only lean slightly towards one or the other. I believe a person does not need 100% certainiy; beyond a reasonable doubt will do.

What If There Is "Something Else"?

I have used the word atheist to mean lack of belief in the God of Abraham, the God of the Bible (and I presume the Koran.) I do this because if you live in a “Western” country that is usually the God someone is referring to when they ask “Do you believe in God.” (I don’t think they want to know if you worship Isis or Zeus or Quetzalcoatl or Shiva.)

Some people will say, "I don’t believe in the God of the Bible, but perhaps there is something else"—A First Cause, A Higher Power, A Supreme Being, or maybe something like “The Force” from Star Wars. What if there is something that we cannot not even conceive of or even have a name for? If you put it that way, I’m an agnostic too. I might even have to be an agnostic about my own existence—maybe I am just something out of the movie, The Matrix, or I’m a character in someone’s dream. What if the whole universe is just a video game and God is just a 12-year old who left his computer running when his mother called him to dinner? I prefer to think in more practical terms.

I believe that atheists should be loud and proud so as to take the stigma from the word atheist, so that the word is no longer an insult.

Please answer this poll question about your belief or non-belief in the Abrahamic God.

Is Atheism a Religion?

Atheism is not a religion. Atheists do not worship anyone or anything. There are no creeds, no rituals.

In particular, atheists are not de facto Satanists. Atheists do not believe in any deities—good ones or evil ones.

Atheists tend not to believe in anything supernatural—no demons, angels, ghosts, fairies, witches, leprechauns, dragons, or unicorns. However, atheism is only defined as a lack of belief in God, so much to my regret, you may come across some atheists who believe in other supernatural entities.

Although atheism is not a religion, some religions may be atheist religions. Some sects of Buddhism do not posit a Supreme Being; neither do some sects of Hinduism. Unitarian Universalism is often non-theistic; it varies from congregation to congregation. Ethical Culture is non-theist.

In the United States, some groups may call themselves a religion for the tax-advantages given to churches or to protest the domination of Christianity.

For instance, the Church of Satan does not profess the existence of the “Dark Lord." They claim the word “Satan” is taken from the Hebrew root of the word which means "opposer" or "one who questions".

Or maybe you have heard of The Church of the Flying Spaghetti Monster (FSM). Pastafarians, as the members of FSM call themselves, describe it as a genuine religion, but it is generally seen as a parody religion created to spoof the ideas of creationism and intelligent design.

What Are Militant Atheists?

Militant atheism is a relatively recent term used to pejoratively describe certain prominent atheists who strongly advocate for atheism. They are not militant in the same way that terrorists are militant (as you might think based on the use of the term “militant”); they merely are willing to publically criticize religion.

In the atheist community, they are called, “The New Atheists.” Sometimes Daniel Dennett (a philosopher and cognitive scientist) Richard Dawkins (a evolutionary biologist) Sam Harris (a philosopher and neuroscientist) and Christopher Hitchens (journalist) are called “The Four Horsemen of the Non-Apocalypse” because they write books promoting the scientific basis for atheism and speak out on behalf of atheism and against religion.

There are many others, but I will leave the enumeration for another essay.

Who Has the Burden of Proof?

The burden of proof is always on the person making the claim. In the case of religion, it is the theist and not the atheist who must show proof. It is, of course, impossible to prove that something does not exist because there is always the possibility that new evidence will turn up. Consequently, it is impossible to prove a negative. However, we can disprove a positive statement if we cannot find evidence to support it. Consequently, in a debate between an atheist and a theist, the atheist will show how the theist has not been able to prove that God exists by refuting the claims and the "evidence" that the theist presents.

All scientists begin with the null hypothesis which is that something does not exist. They then conduct their experiments to try to prove that it does exist. If they are successful in their proof, they express their conclusion as a probability--they usually need a 95% or better probability to reject the null hypothesis. I think that the probability that God exists is so close to 0% that I can confidently say I am an atheist without needing to qualify it by adding the adjective "agnostic" to atheist.

The famous example of this is Russell's Teapot. It was dreamed up by the philosopher Betrand Russell (1872–1970). In order to demonstrate who has the burden of proof in a debate, he claimed that there was a teapot orbiting the sun between Earth and Mars. Who should have to show proof—Russell or the person who did not believe his claim? I'm pretty sure even theists would agree that Russell was the one who needed to provide proof. It is the same with God as it is with teapots.

I object to the term agnostic because theists will interpret that to mean that you are saying "I don't know" in the sense that you have not yet made up your mind.They can also interpret this to mean that you think the possibility that God exists is a 50/50 proposition. I feel it is better to just say "atheist." If you really haven't made up your mind, then just say, "I haven't made up my mind"--you don't need the agnostic label.

Science can't explain everything, and that is OK.

Science can't explain everything, and that is OK.

Science Can’t Explain Everything. Religion Can’t Explain Anything.

Sometimes atheists will be challenged to explain why there is something rather than nothing. I say that is because if there were nothing, we wouldn’t be here to ask the question, but I know that is not the answer they are looking for. The best answer I can give is, “I don’t know, but that doesn’t mean that God is the answer." (“The God of the Gaps” is the term used to attribute any gaps in scientific knowledge as proof of the existence of God.)

Religion is not science or a substitute for science. Religion is fable and myth and metaphor.

A short video clip explains atheism with wit and animation.

Please do this poll.

"Non-theism" means "without God" just as "atheism" does. Since "atheist" often has negative connotations, some may prefer the term "non-theist" because it is less emotionally freighted. Non-theism has the connotation of secular, and is often used to mean that the existence of God is irrelevant ."Non-theistic religions," like some forms of Buddhism, make no claims about God.

"Anti-theist" can have a slightly different meaning. While "atheist" simply means a lack of belief in God, "anti-theist" can mean "actively opposed to theism," and by extension, religions that worship a deity. Not all atheists are anti-theists, but the militant atheists discussed above would probably call themselves anti-theists. David Silverman, the current president of American Atheists, who proudly calls himself a “firebrand,” is another example of an anti-theist.

You may also come across the term "igtheist," "ignostic," or "theological non-cognitivism." These terms refer to the idea that the whole concept of "God" is so irrational that the word can not even be defined--it literally has no meaning--and therefore there is no basis for discussion about belief or disbelief.

One word that is the opposite of theist without the negative connotations is "humanist." Humanism describes a human-centered philosophy in the same way that theism describes a God-centered philosophy. (See the American Humanist Association's webpage, What is Humanism.) "Humanism" usually means "secular humanism," although some people call themselves "religious humanists."

"Freethinker" is a term used to describe someone who forms his opinions through the use of reason, without reference or deference to tradition, authority, or established belief. The word is commonly used to refer to religious beliefs. but can refer to other types of beliefs as well.

Atheism, the word, is very simple. It means without god. Atheism, the concept, is very complex. There are so many nuances and variations.

Why Use the Term Atheist at All?

As the narrator says in the video clip, why do we have the term "atheist" at all? It is one of the few words in English used solely to say what a person is not. (The only other word I could think of was "unmarried.")

The term "atheist" was once solely used as an insult, and it is still used as an insult today. Some people use the word "atheist" the way I use the term "scum" to describe someone who is contemptible. The word "atheist" can stir up these negative associations, although to me the word is perfectly neutral.

I think atheists should "own" the word "atheism", and by doing so, remove the stigma. When theists see that their friends, their neighbors, their co-workers, the people in the sports and entertainment world whom they admire, and even their political representatives are atheists, they may come to realize that atheists are good decent people. They may come to realize that you do not have to be a theist to be a good decent person.

Questions & Answers

Question: I believe in God, but I don't believe in religion. What am I?

Answer: You may be a deist. It depends on exactly what you mean by belief in God. If you believe in God's existence, but you do not believe in a "personal God," you could be a deist.

You may be a "None" This is the term used for people who do not self-identify with any particular religion. Close to one-fourth of Americans are Nones, and their ranks are growing. Some of the Nones are atheists/agnostics, but others believe in God, but are not affiliated with any particular religion. About two-thirds of the Nones believe in God.

You might be "spiritual but not religious." A little over a fourth of Americans describe themselves with this term.

You might even be a pantheist. Do you believe that "God is Nature"? If so, you might be a pantheist. Pantheism is the belief that God is not a separate entity, but rather is found in the entire natural universe.

You could even be an emerging-atheist (to coin a phrase). Giving up religion is the first step to atheism. I hope you will continue on this path.

© 2015 Catherine Giordano

I welcome your comments.

Catherine Giordano (author) from Orlando Florida on September 15, 2018:

Leopoldo wohlman: Thanks for your comment. I agree that we should not accept propositions without evidence. That is why I am an atheist.

Leopoldo wohlman on September 14, 2018:

No matter which way I consider the charts, I seem to always come to the conclusion that faith is the enemy. The idea that we should accept propositions without evidence. Once we go down that road we are surely lost.

Catherine Giordano (author) from Orlando Florida on August 08, 2018:

Warren D Norfleet: Thank you for letting me know you liked my article. I hope you will share it with others.

Warren D Norfleet on August 07, 2018:

Enjoyed Your article, Thank You !!

Catherine Giordano (author) from Orlando Florida on May 10, 2018:

Viv: I love that atheism was included, and near the top of the list at that. It shows that atheism is being given the same recognition and respect as religion. It also means that if you check atheism, you won't have to have an intrusive visit from a chaplain.

I'm sure the questionnaire was voluntary and you didn't need to answer if you didn't want to.

Viv on May 10, 2018:

Included in my hospital appointment letter is a questionnaire about ethnicity, sexual orientation, marital status, gender, disability and religion & belief.

At the top of the list of common religions ( Catholic, Islam etc ) is Atheism.

As I have always considered myself a non- believer I find the inclusion of Atheism odd.

Not only should you declare your beliefs but also your lack of belief. Why ?

Perhaps you can enlighten me as I find this need to know mylack of belief intrusive.

Catherine Giordano (author) from Orlando Florida on March 17, 2018:

stranger on internet: As I said in the article, people can apply whatever label they want for whatever reason they want. But your statement that you don't believe in gravity worries me. Please stay away from bridges and tall billings.

stranger on internet on March 17, 2018:

i think agnostic works for me. i don't have to specifiy what i do or don't believe. its uncomfortable to have to confront others on their own delusions. i don't believe in god but i'm open to proof. i don't believe in no god but am open to proof. i for example also don't believe in gravity. it dosen't require my belief.

Catherine Giordano (author) from Orlando Florida on May 20, 2017:

AshutoshJoshi06: I agree with you. There are way too many words that basically mean atheist. Some feel that atheist is a pejorative word and they want one with positive associations. Some just like to split hairs. Some think that esoteric terms make them sound smart. Thanks for your comment.

Ashutosh Joshi from New Delhi, India on May 17, 2017:

Loved this hub. Though I wonder why we keep adding so many sub divisions or definitions and make things more complex. I mean it begins to give that religious cults sort of feeling.

Two broader views were enough, why add a thousand more definitions. As it is, I am still struggling with my own convictions :)

Catherine Giordano (author) from Orlando Florida on March 24, 2017:

Mr. Anurag: "aw+" is new to me. Since you thanked me for the article, I'm going to assume it means awesome. The plus sign stands for "sum." Thanks.

Catherine Giordano (author) from Orlando Florida on January 18, 2016:

Thanks so much for your comment Mark Brewster. The purpose of this essay was just to explain the various terms that atheists use when talking about what to call themselves. I'm glad I could clear up the meanings of some of the terms for you. I myself learned alot when I researched this.

This piece makes no claims about the existence of God, Jesus Christ, or other deities although I do that elsewhere. Also, I don't get into why atheists don't believe--perhaps I will in another essay.

I'll consider your idea about presuppositional positions. I'll be sure to alert yu that it is published, if and when I do so.

Mark Brewster on January 18, 2016:

Hi, Catherine. VERY well written piece, my friend.

Inevitably, it happens, whenever a thoughtful essay on theism/atheism is penned, that the mix of responders include amateur sad. They cannot seem to comprehend the idea that we disbelieve for a reason OTHER than we "haven't heard the 'Word' well enough, or from the right source" yet.

Normally, I'm pretty 'live and let live' when it comes to personal beliefs. I'm of the opinion that such should be kept private unless asked...and never asked unless the questioner is willing to either accept alternate points of view or engage in 'spirited debate', i.e., argument. (I'll argue in a minute if challenged, but I don't ask.) So, I'll just tell the theists here: unless you want the foundation of your christianity SHREDDED, pass on this comment. Don't even HINT at a motivation for me believing in your god.

WE know, Catherine, the source of the confusion of terms -- and you dealt well with the primaries. (I happen to agree with Sagan, by the way, until/unless persuaded otherwise.)

I've also been curious about the "new atheist" label, having heard references to it in other venues. You explained that well, also -- THANKS!

I enjoy your writing, friend -- perhaps you can bring me up to speed: have you ever done a piece on the presuppositional position? If so, can you link it on FB, and if not, perhaps consider one....when you have a free MONTH, LOL.

Catherine Giordano (author) from Orlando Florida on October 31, 2015:

Thank you FlourishAnyway. What a nice thing to say. I've jsut been so busy. I have ideas for several more hubs. I hope I can get 1-2 done next week.

FlourishAnyway from USA on October 31, 2015:

I sure hope you don't stop writing. I miss your hubs.

JasonKClark on October 17, 2015:

If we're referring to the positive "no god" conviction, then it's not that I, as an agnostic, am without courage in that conviction. It's that I don't hold that conviction, at all. In that case, this statement is a straw man.

If we're referring to a conviction in non belief, then I, as an agnostic, am more than happy to state it to anyone and everyone that I have no belief in "gods". I also have no belief in "no gods". I just don't call that being an a-theist, since I find that method of labelling to be illogical and convoluted. I call it being an agnostic which, to me, screams loud and clear that I don't believe in gods.

Sagan presents a fairly positive view of agnostics, as open minded, elsewhere in Contact:

Ken: "She’s not an atheist. She’s an agnostic. Her mind is open. She’s not trapped by dogma. She’s intelligent, she’s tough, and she’s very professional. The range of her knowledge is broad. She’s just the person we need in this situation."

And, this is the longer quote, for the one I already posted, where he rejects atheism:

"Those who raise questions about the God hypothesis and the soul hypothesis are by no means all atheists. An atheist is someone who is certain that God does not exist, someone who has compelling evidence against the existence of God. I know of no such compelling evidence. Because God can be relegated to remote times and places and to ultimate causes, we would have to know a great deal more about the universe than we do to be sure that no such God exists. To be certain of the existence of God and to be certain of the nonexistence of God seem to me to be the confident extremes in a subject so riddled with doubt and uncertainty as to inspire very little confidence indeed." ~ Conversations with Carl Sagan (2006), edited by Tom Head, p. 70

The extended "I'm agnostic" quote:

“My view is that if there is no evidence for it, then forget about it. An agnostic is somebody who doesn’t believe in something until there is evidence for it, so I’m agnostic.” ~ Carl Sagan, Minneapolis Star-Tribune Profile by Jim Dawson (1996)

A some atheism is "very stupid" quote:

"An atheist has to know a lot more than I know. An atheist is someone who knows there is no god. By some definitions atheism is very stupid." ~

Catherine Giordano (author) from Orlando Florida on October 17, 2015:

JasonKClark: I still like the "courage of your convictions" phrase. I would have to research Sagan's views in detail to see which character (or maybe both) represented his own views.

JasonKClark on October 17, 2015:

//Carl Sagan makes that statement I quoted about agnostics lacking the courage of their conviction in his book "Contact."//

Ah, Contact, but Ellie is the main character, and may better represent Sagan's own views, judging by all his other statements on the topic.

Reverend Joss: "I’ve always thought an agnostic is an atheist without the courage of his convictions."

Ellie: "You could just as well say that an agnostic is a deeply religious person with at least a rudimentary knowledge of human fallibility. When I say I’m an agnostic, I only mean that the evidence isn’t in. There isn’t compelling evidence that God exists—at least your kind of god—and there isn’t compelling evidence that he doesn’t."

//Thank you for your detailed comments. You add even more terms to describe atheism than even the lenghty list I compiled. I like you superman-alien comparison.//


Catherine Giordano (author) from Orlando Florida on October 17, 2015:

JasonKClark: Thank you for your detailed comments. You add even more terms to describe atheism than even the lenghty list I compiled. I like you superman-alien comparison. Carl Sagan makes that statement I quoted about agnostics lacking the courage of their conviction in his book "Contact."

Lawrence Hebb from Hamilton, New Zealand on October 17, 2015:


I'd expect nothing less! Some of the hubs are on the Bible but others are starting to look at what science says!


JasonKClark on October 17, 2015:

I'll take a look, Lawrence. Just so you know...I label myself an agnostic based on the "god" concept, not really "God". I don't think the Bible has proven itself to be anything more than a fanciful tale. Basically...

I consider “God” is to “god” as “Superman” is to “alien”. I do not accept a Superman comic as valid testable evidence for, or against, the existence of “aliens”. I do not accept a Bible as valid testable evidence for, or against, the existence of “gods”. I would not call myself an anti-alienist because I consider “Superman” to be someone's imaginings of what an "alien" might be like. I do not call myself an atheist because I consider “God” to be someone's imaginings of what a "god" might be like.

Lawrence Hebb from Hamilton, New Zealand on October 16, 2015:


I just realized you commented on my reply and I didn't reply, actually I wasn't thinking it!

The last hub I wrote in the subject had me researching the Stoics who argued that it was possible to have purpose without God because to them the universe itself was 'god'

Jason. I agree with you that the onus of proof us on the two extremes and as a 'positive theist' I've done a number of hubs on some of the things we believe point to God's existence that I'd be happy to debate on those hubs.

See you there


JasonKClark on October 16, 2015:

//As Carl Sagan wrote, “Agnostics are atheists who lack the courage of their convictions.”//

That doesn't seem to be a Sagan quote.

"I'm agnostic" ~ Carl Sagan

"To be certain of the existence of god and to be certain of the non-existence of god seem to me to be the confident extremes in a subject so riddled with doubt and uncertainty as to inspire very little confidence indeed." ~ Carl Sagan

From Conversations with Carl Sagan, By Carl Sagan, Tom Head

//I like this scale because it puts "agnostic" in the middle, and defines it as someone who literally thinks that there is a 50/50 chance that God exists or does not exist.//

Dawkins explains that "equiprobable" doesn't equate to 50/50. More like just leaving both options open as having a possibility of not zero.

"Agnosticism is of the essence of science, whether ancient or modern. It simply means that a man shall not say he knows or believes that which he has no scientific grounds for professing to know or believe." ~ Thomas Huxley, 1884

Huxley was a scientist, above all else. He defined agnosticism as a form of demarcation. No objective/testable evidence = an unobjective/unscientific claim. Reults: belief as to the truth, or falsehood, of the claim. While "inconclusive" doesn't answer one way or the other, leaving open the possibility that the claim is true or false, it also doesn't say "50/50" chance. It actually takes s