Like most peoples of the ancient world, the Greeks were polytheists, worshipping a variety of gods and goddesses who were immortal but otherwise acted just like people. Migration, invasion, and colonization brought the Greeks into contact with other peoples and caused their religious beliefs to evolve. How much these contacts shaped Greek religion and other aspects of culture has been the subject of a fierce debate since the late 1980s, when in Black Athena: The Afroasiatic Roots of Classical Civilization, Martin Bernal proposed that the Greeks owed a great deal to the Egyptians and Phoenicians, and that scholars since the nineteenth century had purposely tried to cover this up to make the Greeks seem more European and less indebted to cultures in Africa and Asia.10 Bernal’s ideas are highly controversial, and most classicists do not accept his evidence, but they are part of a larger tendency among scholars in the last several decades — including those who vigorously oppose Bernal — to see the Greeks less in isolation from other groups and more in relation to the larger Mediterranean world.

Greek religion was primarily a matter of ritual, with rituals designed to appease the divinities believed to control the forces of the natural world. Processions, festivals, and sacrifices offered to the gods were frequently occasions for people to meet together socially, times of cheer or even drunken excess.

By the classical era the primary gods were understood to live metaphorically on Mount Olympus, the highest mountain in Greece. Zeus was the king of the gods and the most powerful of them, and he was married to Hera, who was also his sister (just as, in Egypt, Isis was Osiris’s wife and sister). Zeus and Hera had several children, including Ares, the god of war. Zeus was also the father of the god Apollo, who represented the epitome of youth, beauty, and athletic skill, and who served as the patron god of music and poetry. Apollo’s half-sister Athena was a warrior-goddess who had been born from the head of Zeus.

The Greeks also honored certain heroes. A hero was born of a union of a god or goddess and a mortal and was considered an intermediate between the divine and the human. A hero displayed his divine origins by performing deeds beyond the ability of human beings. Herakles (or Hercules, as the Romans called him), the son of Zeus and the mortal woman Alcmene, was the most popular of the Greek heroes, defeating mythical opponents and carrying out impossible (or “Herculean”) tasks. Devotees to Hercules believed that he, like other heroes, protected mortals from supernatural dangers and provided an ideal of vigorous masculinity.

The polis administered cults and festivals, and everyone was expected to participate in what were events similar to today’s patriotic parades or ceremonies. Much religion was local and domestic, and individual families honored various deities privately in their homes. Many people also believed that magic rituals and spells were effective and sought the assistance of individuals reputed to have special knowledge or powers to cure disease, drive away ghosts, bring good weather, or influence the actions of others. Even highly educated Greeks sought the assistance of fortune-tellers and soothsayers, from the oracle at Delphi to local figures who examined the flights of birds or the entrails of recently slaughtered chickens for clues about what was going to happen in the future.

Along with public and family forms of honoring the gods, some Greeks also participated in what later historians have termed mystery religions, in which participants underwent an initiation ritual and gained secret knowledge that they were forbidden to reveal to the uninitiated. The Eleusinian mysteries, held at Eleusis in Attica, are one of the oldest of these. They centered on Demeter, the goddess of the harvest, whose lovely daughter Persephone (Per-SEH-foh-nee), as the story goes, was taken by the god Hades to the underworld. In mourning, Demeter caused drought, and ultimately Zeus allowed Persephone to return to her, though she had to spend some months of the year in Hades. There is evidence of an agrarian ritual celebrating this mythological explanation for the cycle of the seasons as early as the Bronze Age, and in the sixth century B.C.E. the rulers of nearby Athens made the ritual open to all Greeks, women and slaves included. Many people flocked to the annual ceremonies and learned the mysteries, which by the fourth century B.C.E. appear to have promised life after death to those initiated into them.

Another somewhat secret religion was that of Dionysus (digh-uh-NIGH-suhs), the god of wine and powerful emotions. Dionysus appears to have been a god of non-Greek origin, though stories evolved to fit him into the Olympian system as a son of Zeus. He was killed and then reborn, which is why he, like Persephone, became the center of mystery religions offering rebirth. As the god of wine, he also represented freedom from the normal constraints of society, and his worshippers were reported to have danced ecstatically and even to have become a frenzied and uncontrolled mob. Whether or how often this actually happened is impossible to know, as contemporary Athenian writers who did not approve may have embellished their accounts of these wild rituals, and later scholars sometimes regarded them simply as fiction because chaotic orgies did not fit with their notions of the rational and orderly Greeks.

Greeks also shared some public Pan-Hellenic festivals, the chief of which were held at Olympia in honor of Zeus and at Delphi in honor of Apollo. The festivities at Olympia included athletic contests that have inspired the modern Olympic games. Held every four years, these games were for the glory of Zeus. They attracted visitors from all over the Greek world and lasted until the fourth century C.E., when they were banned by a Christian emperor because they were pagan. The Pythian (PIH-thee-uhn) games at Delphi were also held every four years and emphasized musical and literary contests as well as athletic prowess. Both the Olympic and the Pythian games were unifying factors in Greek life, bringing Greeks together culturally as well as religiously.