In the attempt to explain plant and animal life, Aristotle formulated the theory that a special form of animating principle was involved. The "élan vital" of Bergson and the theory of Joad are modern reiterations of this conception. Aristotle is not quite consistent when he attempts to give us his theistic beliefs. At times God is, for him, a mysterious spirit that never does anything and has not any desire or will. Elsewhere, he conceives God as pure energy; a prime mover unmoved. Certain modern physicists still cling to this Aristotelian god. This conception of a deity was far from the beliefs of his age, and it is not strange that Aristotle was charged with impiety and with having taught that prayer and sacrifice were of no avail. He fled from Athens and shortly afterwards died in exile.
These three supreme Greek thinkers, Socrates, Plato, and Aristotle, have not contributed a single argument for the existence of a supreme being which is now not discredited. Socrates relied on the now outmoded argument from design; and only in a greatly modified form are the arguments of Plato and Aristotle accepted by modern theists. Holding such heretical views in an age when history was a frail fabric of legends, and the scientific explanation of nature in its extreme infancy, what would their views be today?
In the consideration of the Greek thinkers of lesser importance one finds that they were continually storming against the religious conceptions of the populace. The philosophers were ever unpopular with the credulous. "Damon and Anaxagoras were banished; Aspasia was impeached for blasphemy and the tears of Pericles alone saved her; Socrates was put to death; Plato was obliged to reserve pure reason for a chosen few, and to adulterate it with revelation for the generality of his disciples; Aristotle fled from Athens for his life, and became the tutor of Alexander." (Winwood Reade: "The Martyrdom of Man.")
Anaxagoras, the friend and master of Pericles, Euripides, and Socrates, was accused by the superstitious Athenians of atheism and impiety to the gods. He was condemned to death and barely escaped this fate through the influence of Pericles; which resulted in the accusation of atheism against Pericles. Euripides was accused of heresy, and Aeschylus was condemned to be stoned to death for blasphemy and was saved from this fate by his brother Aminias. The philosophy of Parmenides was distinctly pantheistic, and Pythagoras, who attempted to purify the religion of the Greeks and free it from its absurdities and superstitions, was exiled for his scepticism.
Democritus, a materialist and atheist of 2500 years ago, formulated a mechanical view of phenomena in accordance with which everything that happens is due to physical impacts. "Such a materialism was a great liberation from superstition; and had it survived in its integrity, the path of European wisdom would have been vastly different from what it was. What the path would have been, we are beginning to see to-day, for since the nineteenth century we have been treading it more or less consistently but by no means so gallantly and courageously as Democritus." (G. Boas: "The Adventures of Human Thought.")
Democritus and the Epicureans strove to deliver men from their two chief apprehensions: the fear of the gods, and the fear of death; and in so doing rejected the religious beliefs and substituted a rational and scientific conception of the universe.
It was Xenophanes, the Voltaire of Greece, who brought to the attention of his countrymen the discovery that man created the gods in his own image. He attacked the conceptions of the Greek deities with these words, "Mortals deem that the gods are begotten as they are, and have clothes like theirs, and voice and form ... Yes, and if oxen and horses or lions had hands, and could paint with their hands, and produce works of art as men do, horses would paint the forms of the gods like horses, and oxen like oxen, and make their bodies in the image of their several kinds.... The Ethiopians make their gods black and snub-nosed; the Thracians say theirs have blue eyes and red hair."
Considering Greek philosophy in its entirety, we see that it was naturalistic rather than supernaturalistic, and rationalistic rather than mystical. These gifted men saw no clear indication for the existence of a supreme being; very few of them speak of the deity in the role of Providence and fewer still believed in personal immortality.
Professor Boas, in contrasting Asiatic mythology with Greek philosophy, remarks: "The Asiatic myths assumed the existence of beings beyond the world, not subject to mundane laws, who made and controlled the course of events. There was no reason why they should have made a world. They seemed to be living as divine a life without it as with it. The question was one which persisted in Asiatic thought, and when Christianity became dominant in Europe, much of its theologians' time was spent in answering it. The only plausible answer then was that God made the world because He felt like it. For no reason could be given sufficiently compelling to sway the will of the Omnipotent. But such an answer was unsatisfactory to the Greek. In his philosophy all this is changed. No god steps out of the machine to initiate cosmic history. The First Cause is a physical substance, some material thing, which operates by the laws of its own nature. Its every movement is theoretically open to the scrutiny of reason. And hence, a scientific rather than a religious answer can be given to every question."
At the beginning of the Christian era, the cultured Romans were stoics or epicureans. The poet Lucretius was an epicurean who regarded the belief in the gods as a product of the terrors of primitive man and recommended that the mind should be emancipated from the fear of the gods and argued against the immortality of the soul. Seneca, Epictetus, and Marcus Aurelius were stoics. Cicero insinuates that the gods are only poetical creations, that the popular doctrine of punishment in a world to come is only an idle fable, and is uncertain whether the soul is immortal. Seneca wrote against the religion of his country, and the philosophy of cultured Romans of the time of the physician Galen tended towards atheism.