The main religion was polytheism, meaning they believed in several Gods. The people of Sparta followed the beliefs of the Olympians. In ancient Greek religion, the Twelve Olympians were the principal deities of the Greek pantheon residing on the top of Mount Olympus: Zeus, Hera, Poseidon, Demeter, Athena, Apollo, Artemis, Ares, Aphrodite, Hephaestus, Hermes, Hestia, and Dionysus.