If there was one aspect of the Hellenistic civilization which served more than others to accent the contrast with Hellenic culture, it was the new trend in religion. The civic religion of the Greeks as it was in the age of the city-states had now almost entirely disappeared. For the majority of the intellectuals its place was taken by the philosophies of Stoicism, Epicureanism, and Skepticism. Some who were less philosophically inclined turned to the worship of Fortune or became followers of dogmatic atheism. Among the masses a tendency to embrace the emotional religions of Oriental origin was even more clearly manifest. The Orphic and Eleusinian mystery cults attracted more votaries than ever before. The worship of the Egyptian mother-goddess Isis threatened for a time to reach the proportions of a world religion. The astral religion of the Chaldeans likewise spread rapidly, with the result that its chief product, astrology, was received with fanatical enthusiasm throughout the Hellenistic world. So strong was its appeal that it had much to do with the eclipse of science and reason in the second and first centuries B.C. But the most powerful influence of all came from the offshoots of Zoroastrianism, especially from Mithraism and Gnosticism. While all of the cults of Oriental origin resembled each other in their promises of salvation in a life to come, Mithraism and Gnosticism had a more ethically significant mythology, a deeper contempt for this world, and a more clearly defined doctrine of redemption through a personal savior.

These were the ideas which satisfied the emotional cravings of the common people, convinced as they were of the worthlessness of this life and ready to be lured by extravagant promises of better things in a world to come. If we can judge by conditions in our own time, some of the doctrines of these cults must have exerted their influence upon members of the upper classes also. Even the most casual observer of modern society knows that pessimism, mysticism, and otherworldliness are not confined to the downtrodden. In some cases the keenest disgust with this life and the deepest mystical yearnings are to be found among those whose pockets bulge with plenty.

A factor by no means unimportant in the religious developments of the Hellenistic Age was the dispersion of the Jews. As a result of Alexander's conquest of Palestine in 332 b.c. and the Roman conquest about three centuries later, thousands of Jews migrated to various sections of the Mediterranean world. It has been estimated that 1,000,000 of them lived in Egypt in the first century a.d. and 200,000 in Asia Minor. They mingled freely with other peoples, adopting the Greek language and no small amount of the Hellenic culture which still survived from earlier days. At the same time they played a major part in the diffusion of Oriental beliefs. Their religion had already taken on a spiritual and messianic character as a result of Persian influence. Their leading philosopher of this time, Philo Judaeus of Alexandria, developed a body of doctrine representing the farthest extreme which mysticism had yet attained. Many of the Hellenistic Jews eventually became converts to Christianity and were largely instrumental in the spread of that religion outside of Palestine.