Atheism and Skepticism in Ancient Greece

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Ancient Greece was an exciting time for ideas and philosophy — perhaps for the first time, there developed a social system sufficiently advanced to let people sit around and think about difficult topics for a living. It's no surprise that people thought about traditional notions of gods and religion, but not everyone decided in favor of tradition. Few if any could strictly be called atheist philosophers, but they were skeptics who were critical of traditional religion.


Protagoras is the first such skeptic and critic of whom we have a reliable record. He coined the famous phrase "Man is the measure of all things." Here is the full quote:

"Man is the measure of all things, of things that are that they are, of things that are not that they are not."

This seems like a vague claim, but it was quite unorthodox and dangerous at the time: placing men, not gods, at the center of value judgments. As proof of just how dangerous this attitude was perceived, Protagoras was branded with impiety by Athenians and banished while all his works were collected and burnt.

Thus, what little we know about comes from others. Diogenes Laertius reported that Protagoras also said:

"As to the gods, I have no means of knowing either that they exist or do not exist. For many are the obstacles that impede knowledge, both the obscurity of the question and the shortness of human life."

That's a good motto for agnostic atheism, but it remains an insight that few people even today can accept.


Aristophanes (c. 448-380 BCE) was an Athenian playwright and is considered one of the greatest writers of comedy in literary history. Curiously enough for a critic of religion, Aristophanes was noted for his conservatism. At one point he is quoted as saying:

"Open your mouth and shut your eyes, and see what Zeus shall send you."

Aristophanes was known for his satire, and this might be a satirical comment on all those who claim to have a god speaking through them. Another comment is more clearly critical and perhaps one of the earliest "burden of proof" arguments:

"Shrines! Shrines! Surely you don't believe in the gods. What's your argument? Where's your proof?"

You can hear atheists today, over two millennia later, asking the same questions and getting the same silence as an answer.


Aristotle (384-322 BCE) was a Greek philosopher and scientist who shares with Plato and Socrates the distinction of being the most famous of ancient philosophers. In his Metaphysics, Aristotle argued for the existence of a divine being, described as the Prime Mover, who is responsible for the unity and purposefulness of nature.

Aristotle is on this list, however, because he was also quite skeptical and critical of more traditional ideas of gods:

"Prayers and sacrifices to the gods are of no avail"
"A tyrant must put on the appearance of uncommon devotion to religion. Subjects are less apprehensive of illegal treatment from a ruler whom they consider god-fearing and pious. On the other hand, they do less easily move against him, believing that he has the gods on his side."
"Men create gods in their own image, not only with regard to their form but with regard to their mode of life."

So while Aristotle was by no means an "atheist" in the strictest sense, he was not a "theist" in the traditional sense — and not even in what today would be called the "traditional" sense. Aristotle's theism is closer to a deistic sort of theism which was popular during the Enlightenment and which most orthodox, traditionalist Christians today would regard as little different from atheism. On a purely practical level, it probably isn't.

Diogenes of Sinope

Diogenes of Sinope (412?-323 BCE) is the Greek philosopher who is generally considered the founder of Cynicism, an ancient school of philosophy. Practical good was the goal of Diogenes' philosophy and he did not hide his contempt for literature and the fine arts. For example, he laughed at men of letters for a reading of the sufferings of Odysseus while neglecting their own.

This disdain carried right over to religion which, for Diogenes of Sinope, had no apparent relevance to daily life:

"Thus does Diogenes sacrifice to all the gods at once." (while cracking a louse on the altar rail of a temple)
"When I look upon seamen, men of science, and philosophers, man is the wisest of all things. When I look upon priests, prophets, and interpreters of dreams, nothing is so contemptible as a man."

This contempt for religion and gods is shared by many atheists today. Indeed, it's hard to describe this contempt as any less harsh than the criticism of religion which so-called "New Atheists" express today.


Epicurus (341-270 BCE) was a Greek philosopher who founded the school of thought called, appropriately enough, Epicureanism. The essential doctrine of Epicureanism is that pleasure is the supreme good and goal of human life. Intellectual pleasures are placed above sensual ones. True happiness, Epicurus taught, is the serenity resulting from the conquest of fear of the gods, of death, and of the afterlife. The ultimate aim of all Epicurean speculation about nature is thus to rid people of such fears.

Epicurus did not deny the existence of gods, but he argued that as "happy and imperishable beings" of supernatural power they could have nothing to do with human matters — though they might take pleasure in contemplating the lives of good mortals.

"Fabulous persuasion in faith is the approbation of feigned ideas or notions; it is credulous belief in the reality of phantoms."
"...Men, believing in myths, will always fear something terrible, everlasting punishment as certain or probable. ...Men base all these fears not on mature opinions, but on irrational fancies, so that they are more disturbed by fear of the unknown than by facing facts. Peace of mind lies in being delivered from all these fears."
"A man cannot dispel his fear about the most important matters if he does not know what is the nature of the universe but suspects the truth of some mythical story. So that without natural science it is not possible to attain our pleasures unalloyed."
"Either God wants to abolish evil, and cannot; or he can, but does not want to. ...If he wants to, but cannot, he is impotent. If he can, but does not want to, he is wicked. ...If, as they say, God can abolish evil, and God really wants to do it, why is there evil in the world?"

Epicurus' attitude towards gods is similar to that usually ascribed to the Buddha: gods may exist, but they can't help us or do anything for us so there is no point in worrying about them, praying to them, or looking to them for any aid. We humans know we exist here and now so we need to worry about how to best live our lives here and now; let the gods — if there are any — take care of themselves.

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Cline, Austin. "Atheism and Skepticism in Ancient Greece." Learn Religions, Oct. 20, 2021, Cline, Austin. (2021, October 20). Atheism and Skepticism in Ancient Greece. Retrieved from Cline, Austin. "Atheism and Skepticism in Ancient Greece." Learn Religions. (accessed March 26, 2023).