A deity is a postulated preternatural or supernatural being, who is always of significant power, worshipped, thought holy, divine, or sacred, held in high regard, and respected by human beings. Deities assume a variety of forms, but are frequently depicted as having human or animal form. Some faiths and traditions consider it blasphemous to imagine or depict the deity as having any concrete form. They are usually immortal. They are commonly assumed to have personalities and to possess consciousness, intellects, desires, and emotions similar to those of humans. Such natural phenomena as lightning, floods, storms, other 'acts of God', and miracles are attributed to them, and they may be thought to be the authorities or controllers of every aspect of human life (such as birth or the afterlife). Some deities are asserted to be the directors of time and fate itself, to be the givers of human law and morality, to be the ultimate judges of human worth and behavior, and to be the designers and creators of the Earth or the universe.
Theories and narratives about, and modes of worship of, deities are largely a matter of religion. At present, the vast majority of humans are adherents of some religion, and this has been true for at least thousands of years. Human burials from between 50,000 and 30,000 B.C. provide evidence of human belief in an afterlife and possibly in deities, although it is not clear when human belief in deities became the dominant view.
Some deities are thought to be invisible or inaccessible to humans—to dwell mainly in otherworldly, remote or secluded and holy places, such as Heaven, Hell, the sky, the under-world, under the sea, in the high mountains or deep forests, or in a supernatural plane or celestial sphere. Typically, they rarely reveal or manifest themselves to humans, and make themselves known mainly through their effects. Monotheistic deities are often thought of as being omnipresent, though invisible.
Often people feel an obligation to their deity, although some view their deity as something that serves them.
Folk religions usually contain active and worldly deities.
In polytheism, deities are conceived of as a counterpart to humans. In the reconstructed and hypothetical Proto-Indo-European, humans were described as chthonian ("earthly") as opposed to the deities which were deivos ("celestial"). This almost symbiotic relationship is present in many later cultures: humans are defined by their station subject to the deities, nourishing them with sacrifices, and deities are defined by their sovereignty over humans, punishing and rewarding them, but also dependent on their worship.
The boundary between human and divine in most cultures is by no means absolute. Demigods are the offspring from a union of a human with a deity, and most royal houses in Antiquity claimed divine ancestors.
Beginning with Djedefra (26th century BC), the Egyptian pharaohs called themselves "Son of Ra" as well as "Bull (son) of his Mother" among their many titles. One, Hatshepsut, who ruled from 1479 BC to 1458 BC, traced her heritage not only to her father, Thutmose I, who would have become deified upon his death—but also to the deity, Mut, as a direct ancestor.
Some human rulers, such as the pharaohs of the New Kingdom, the Japanese Tennos, and some Roman Emperors have been worshipped by their subjects as deities while still alive. The earliest ruler known to have claimed divinity is Naram-Sin (22nd century BC). In many cultures, rulers and other prominent or holy persons may be thought to become deities upon death (see Osiris, ancestor worship, canonization).
Some religions are monotheistic and assert the existence of a unique deity. In the English language, the common noun god is equivalent to deity, while the proper noun God (capitalized) references the unique deity of monotheism. Pantheism considers the universe itself to be a deity. Dualism is the view that there are two deities: a deity of good who is opposed and thwarted by a deity of evil, of equal power. Manichaeism, Zoroastrianism, and Gnostic sects of Christianity are, or were, dualist. Polytheism asserts the existence of several deities, who together form a pantheon. Monolatry is a type of polytheism in which deities are believed to exert power only on those who worship them. Henotheism is a form of monolatry in which one deity is worshipped as supreme. Animism is the belief that spirits inhabit every existing thing, including plants, minerals, animals, and, including all the elements, air, water, earth, and fire. The anthropologist E. B. Tylor argued that religion originally took an animist form. Theism is the view that at least one deity exists.
It may not be readily apparent what form a religion takes. Religions that avow monotheism may, in fact, be henotheistic in that they recognize the existence of several echelons of supernatural, immortal beings in addition to the central deity, such as angels, saints, Satan, demons, and devils, although these beings may not be considered deities. Adherents of polytheistic religions, such as certain schools of Hinduism, may regard all deities in the pantheon as manifestations, aspects, or multiple personalities of the single supreme deity, and the religions may be more akin to pantheism, monotheism, or henotheism than is initially apparent to an observer.
The many religions do not generally agree on which deities exist, although sometimes the pantheons may overlap, or be similar except for the names of the deities. It is frequently argued that Judaism, Christianity, and Islam all worship the same monotheistic deity, although they differ in many important details. Comparative religion studies the similarities and contrasts in the views and practices of various religions. Philosophy of religion discusses philosophical issues related to theories about deities. Narratives about deities and their deeds are referred to as myths, the study of which is mythology. The word "myth" has an overtone of fiction, so religious people commonly (although not invariably) refrain from using this term in relation to the stories about deities which they themselves believe in.
In Buddhism, devas are beings inhabiting certain happily-placed worlds of Buddhist cosmology. These beings are mortal (being part of ), numerous, and are not worshipped; it is also common for Yidams to be called deities, although the nature of Yidams are distinct from what is normally meant by the term.
The Buddhist Madhyamaka argue strongly against the existence of a universal creator or essential being (such as Brahman), yet Buddhists are not atheist or agnostic - due to these terms being strongly tied to concepts of existence. Some Prasangikas hold that even the conventional existence of universal (monotheistic) deities is a non-existent, whereas others consider that the conventional existence of such a being is an existent.
Some modern Buddhists, especially in the west, believe that deities exist in the same manner that elves or unicorns do - as an archetypal consensual entity that serves a symbolic purpose in the popular imagination.
Though this may seem a rather weak basis of existence for some, as Buddhists (such as the Yogacara) deny any objective existence (of e.g. a chair), and many more deny any sort of essential existence of phenomena at all, the distinction between the existence and non-existence of consensual entities is important to Buddhist philosophy. However, a necessary requirement of Candrakirti's (Prasangika) view is that existents must not conflict with essencelessness, and it is generally agreed by them that monotheistic assertions of deity do not make much sense without some assertion of essence, which itself is vehemently rejected, so thereby monotheistic (objectively/essentially existing) deities are non-existent even in a conventional sense.
In this view, God (Allah, Brahman, Elohim, Jesus Christ, Waheguru, etc) is not a deity, and the anthropomorphic myths and iconography associated with him are regarded as symbolism, allowing worshippers to speak and think about something which otherwise would be beyond human comprehension.
There also are many such deities from ancient times, such as in Egypt, Greece, and Rome who were "the" local or regional deity, and who became lost in our view of these cultures only as a whole. According to Plutarch, who lived from circa 46 - 120 A.D., the Egyptian temple of Neith bore the inscription: I am All That Has Been, That Is, and That Will Be. No mortal has yet been able to lift the veil that covers Me. This is a creator deity who was worshipped by devotees in the western delta region of Egypt for over three thousand years. That worship assigned many roles to the deity and took many forms—even including one of earliest known oracle traditions and a resurrection cult—and that worship spread to other regions of Egypt and, some suspect, to other ancient cultures that arose during the beginning of recorded human history. Herodotus describes the annual festival of lights associated with this deity in late December—thousands of years after the earliest records attest an already-established worship of the deity.
Not many of these endured so long, but records of such deities exist from the beginning of human records of their beliefs. Tantalizing images of what may be tens of thousands of years of worship of deities who seem to have been unchallenged and essentially unchanged, therefore easily suggesting that perhaps, humans believed in a single deity initially, that some later developed pantheons and returned again to single deities, and that others developed cosmological concepts that were quite abstract and not dependent upon deities.
Likewise, Emile Durkheim was one of the earliest to suggest that Gods represent an extension of human social life to include supernatural beings. In line with this reasoning, psychologist Matt Rossano contends that when humans began living in larger groups, they may have created gods as a means of enforcing morality. In small groups, morality can be enforced by social forces such as gossip or reputation. However it is much harder to enforce morality using social forces in much larger groups. He indicates that by including ever watchful gods and spirits, humans discovered an effective strategy for restraining selfishness and building more cooperative groups.