Title: Ancient Greek religion
Content:   Ancient Greek religion encompasses the collection of beliefs, rituals, and mythology originating in ancient Greece in the form of both popular public religion and cult practices. The application of the modern concept of "religion" to ancient cultures has been questioned as anachronistic. The ancient Greeks did not have a word for 'religion' in the modern sense. Likewise, no Greek writer known to us classifies either the gods or the cult practices into separate 'religions'. Instead, for example, Herodotus speaks of the Hellenes as having "common shrines of the gods and sacrifices, and the same kinds of customs." Most ancient Greeks recognized the twelve major Olympian gods and goddesses—Zeus, Hera, Poseidon, Demeter, Athena, Ares, Aphrodite, Apollo, Artemis, Hephaestus, Hermes, and either Hestia 
Title: Hellenism (modern religion)
Content:   Hellenism (Ἑλληνισμός) in a religious context refers to the modern pluralistic religion practiced in Greece and around the world by several communities, derived from the beliefs, mythology and rituals from antiquity through and up to today. It is a system of thought and spirituality with a shared culture and values, and common ritualistic, linguistic and literary tradition. More broadly, Hellenism centers itself around the worship of Hellenic deities, namely the twelve Olympians. Greeks that identify their religion and way of life with Hellenism are commonly referred to as Εθνικοί Έλληνες (Ethnic Hellenes). Non-Greek devotees of the Greek gods who embody Hellenic ideals are commonly referred to as Hellenists. More generally, someone who worships the Greek gods but does not necessarily adhere to Hellenic ideals, ethos or ritual may be referred as a "Hellenic" polytheist or pagan. Pagan and paganism are considered to be insulting 
Title: Deity
Content:  The ancient Greeks revered both gods and goddesses. These continued to be revered through the early centuries of the common era, and many of the Greek deities inspired and were adopted as part of much larger pantheon of Roman deities. The Greek religion was polytheistic, but had no centralized church, nor any sacred texts. The deities were largely associated with myths and they represented natural phenomena or aspects of human behavior. Several Greek deities probably trace back to more ancient Indo-European traditions, since the gods and goddesses found in distant cultures are mythologically comparable and are cognates. Eos, the Greek goddess of the dawn, for instance, is cognate to Indic Ushas, Roman Aurora and Latvian Auseklis. Zeus, the Greek king of gods, is cognate to 
Title: Ancient Greece
Content:  Religion was a central part of ancient Greek life. Though the Greeks of different cities and tribes worshipped similar gods, religious practices were not uniform and the gods were thought of differently in different places. The Greeks were polytheistic, worshipping many gods, but as early as the sixth century BC a pantheon of twelve Olympians began to develop. Greek religion was influenced by the practices of the Greeks' near eastern neighbours at least as early as the archaic period, and by the Hellenistic period this influence was seen in both directions. The most important religious act in ancient Greece was animal sacrifice, most commonly of sheep and goats. Sacrifice was accompanied by public prayer, and prayer and hymns were themselves a major part of ancient Greek religious life.
Title: Classics
Content:  cult practices. These different groups varied enough for it to be possible to speak of Greek religions or "cults" in the plural, though most of them shared similarities. Also, the Greek religion extended out of Greece and out to neighbouring islands. Many Greek people recognized the major gods and goddesses: Zeus, Poseidon, Hades, Apollo, Artemis, Aphrodite, Ares, Dionysus, Hephaestus, Athena, Hermes, Demeter, Hestia and Hera; though philosophies such as Stoicism and some forms of Platonism used language that seems to posit a transcendent single deity. Different cities often worshipped the same deities, sometimes with epithets that distinguished them and specified their local nature.
Title: Ancient Greek religion
Content:  "There was no centralization of authority over Greek religious practices and beliefs; change was regulated only at the civic level. Thus, the phenomenon we are studying is not in fact an organized “religion.” Instead we might think of the beliefs and practices of Greeks in relation to the gods as a group of closely related “religious dialects” that resembled each other far more than they did those of non-Greeks."
Title: Hellenism (modern religion)
Content:  Hellenism has historically been a pluralistic religion with beliefs ranging between polytheism, animism and monism, although a Hellenist may hold beliefs that fall into all of these categories. Additionally, there are other interpretations of divinity in line with Hellenistic philosophies, like Epicureanism. Hellenism is, in practice, primarily centered around polytheistic and animistic worship. Devotees worship the Greek gods, which comprise the Olympians, divinities and spirits of nature (such as nymphs), underworld deities (chthonic gods) and heroes. Both physical and spiritual ancestors are greatly honored. The gods exhibit both universal and local qualities. For the Greeks, "their gods were at the same time universal, found everywhere and powerful over the whole world, and intensely local, manifesting themselves in particular places."
Title: Greece
Content:  The numerous gods of the ancient Greek religion as well as the mythical heroes and events of the ancient Greek epics (The Odyssey and The Iliad) and other pieces of art and literature from the time make up what is nowadays colloquially referred to as Greek mythology. Apart from serving a religious function, the mythology of the ancient Greek world also served a cosmological role as it was meant to try to explain how the world was formed and operated. The principal gods of the ancient Greek religion were the Dodekatheon, or the Twelve Gods, who lived on the top of Mount Olympus. The most important of all ancient Greek gods was Zeus, the king of the gods, who was married to his sister, Hera. The other Greek gods that made up the Twelve Olympians were Ares, Poseidon, Athena, Demeter, Dionysus, Apollo, Artemis, Aphrodite, Hephaestus, and Hermes. Apart from these twelve gods, Greeks also had a variety of other mystical beliefs, such as nymphs and other magical creatures.
Title: Hellenism (modern religion)
Content:  when referring to ethnic Hellenes who practice Hellenism. Hellenic religion has manifested itself as legal bodies in Greece through the names Hellenic Ethnic Religion and Ancient Hellenic Religion. In the USA, the religion has manifested itself through the organizations such as Hellenion. More broadly, Hellenic Polytheism describes groups, and individuals who "reinterpret and reinvent ancient Greek religious practices and identities." Olympianismos (Olympianism) and Neopaganismos (Neopaganism)" are used by the Greek Orthodox Church in a derogatory manner, while the term Dodekatheismos (religion of twelve gods) is used by both Christian critics and some polytheists." Various religious movements reviving or reconstructing ancient Greek religious practices have been publicly emerging since the 1990s. In 2017, Greece legally recognized Hellenism as a "known religion", granting it certain religious freedoms in that country, including the freedom to open houses of worship and for clergy to officiate at weddings.
Title: Iliad
Content:  teacher which were popular origins of existing religions in the world. The individuals were free to believe what they wanted, as the Greek religion was created out of a consensus of the people. These beliefs coincide to the thoughts about the gods in polytheistic Greek religion. Adkins and Pollard (2020/1998), agree with this by saying, "the early Greeks personalized every aspect of their world, natural and cultural, and their experiences in it. The earth, the sea, the mountains, the rivers, custom-law (themis), and one's share in society and its goods were all seen in personal as well as naturalistic terms." As a result of this thinking, each 

Question: what is it called when you believe in greek gods?
Answer: Hellenism.
Hellenic polytheist.
Hellenic Polytheism.