A deity or a god, is a postulated Preternatural being, usually, but not always, of significant power, worshipped, thought holy, Divine, or Sacred, held in high regard, or respected by Human beings. They assume a variety of forms, but are frequently depicted as having human or animal form. Sometimes it is considered blasphemous to imagine 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 much like 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. Some of these "gods" have no power at all-they are simply worshipped.
Folk religions usually contain active and worldly deities.
In polytheism, gods are conceived of as a counterpart to humans. In the reconstructed and hypothetical Proto-Indo-European, humans were described as tkonion, "earthly", as opposed to the gods which were deivos, "celestial". This almost symbiotic relationship is present in many later cultures: humans are defined by their station subject to the gods, nourishing them with sacrifices, and gods 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". 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 god. In the English language, the common noun "god" is equivalent to "deity", while "God" (capitalized) is the name of 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 gods, who together form a pantheon. Henotheism is a form of polytheism in which one god is worshipped as supreme. Monolatrism is a type of polytheism in which gods are believed to exert power only on those who worship them. 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 god exists. Atheism is either the denial of the existence of gods or God, or the absence of the belief that there are gods or God.
It may not be readily apparent what form a religion actually takes. Religions that avow monotheism may in fact be henotheistic in that they recognize the existence of several echelons of supernatural, immortal, deity-like beings in addition to the supreme God, 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 gods in the pantheon as manifestations, aspects, or multiple personalities of the single supreme god, and the religions may be more akin to monotheism or henotheism than is initially apparent to an observer.
The many religions do not in general agree on which gods exist, although sometimes the pantheons may overlap, or be similar except for the names of the gods. It is frequently argued that Judaism, Christianity, and Islam all worship the same monotheistic god, although they differ in many important details. Comparative religion studies the similarities and contrasts in the views and practices of various religions. The Philosophy of religion discusses philosophical issues related to theories about gods. Narratives about gods 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 gods in which they believe themselves.
In Buddhism gods are the beings in God realm of Samsara, these beings are mortal, 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.
Many modern Buddhists consider that deities (and God) exist in the same manner that elves or unicorns do - as an archetypal consensual entity that serves a purpose in the popular imagination; and in this limited sense, God exists.
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) gods are non-existent even in a conventional sense. Of course these arguments are more to do with the delineation of the definition of existence than anything else.
In this view, God (Allah, Brahman, Waheguru, Elohim, etc...) is not a god or deity, and the anthropomorphic mythology and iconography associated with Him is regarded as Symbolism, allowing worshippers to speak and think about something which otherwise would be beyond human comprehension.