Greek religion encompasses the collection of beliefs and rituals practiced in ancient Greece in form of cult practices. It is therefore the practical counterpart of Greek mythology. Within the Greek world, religious practice varied enough so that one might speak of Greek religions. The cult practices of the Hellenes extended beyond mainland Greece, to the islands and coasts of Ionia in Asia Minor, to Magna Graecia (Sicily and southern Italy), and to scattered Greek colonies in the Western Mediterranean, such as Massalia (Marseille). Greek examples tempered Etruscan cult and belief to inform much of the Roman religion.

The Greek people recognized the 13 major Gods: Zeus, Hera, Poseidon, Apollo, Artemis, Aphrodite, Ares,Dionysus Hephaestus, Athena, Hermes, Demeter, and Hestia. Different cities worshipped different deities, sometimes with epithets that specified their local nature; Athens had Athena; Hades, Nike and Artemis; Corinth was a centre for the worship of Aphrodite; Delphi and Delos had Apollo; Olympia had Zeus, and so on down to the smaller cities and towns. Identity of names was not a guarantee of a similar cult; the Greeks themselves were well aware that Artemis was worshipped at Sparta; the virgin huntress was a very different deity from the Artemis who was a many-breasted fertility goddess at Ephesus. When literary works such as the Iliad related conflicts among the gods these conflicts were because their followers were at war on earth and were a celestial reflection of the earthly pattern of local deities. Though the worship of the major deities spread from one locality to another, and though larger cities boasted temples to several major gods, the identification of different gods with different places remained strong to the end.

Christianization

In the late 4th century A.D the Imperial courts were predominantly Christian; the Christian emperors closed pagan oracles, temples and ended the pagan games by decrees, in a series of increasingly stringent decrees. Finally, the public practice of the Greek religion was made illegal by the Emperor Theodosius I and this was enforced by his successors. The Greek religion was stigmatized as "paganism" and it survived only in rural areas and in forms that were submerged in Christianized rite and ritual, as Europe entered into the Dark Ages.

The European Renaissance scarcely touched Greece. Renaissance humanism in Italy and Western Europe included the rediscovery and reintroduction of the culture and learning of ancient Greek thought and philosophy, which included a renewed appreciation of the ancient religion and myth, reinterpreted from a humanist point-of-view.