Hinduism
In Hinduism, the manifestations of Vishnu as a human being are referred to as Vishnu's avatars. As such, they are similar to Jesus, whose manifestation on Earth is referred to in Christianity as Christ's incarnation. The most popular avatar of Vishnu in Hinduism is Krishna. The most well-known theophany is contained within the Bhagavad-Gita, itself representing one chapter of the larger epic, the Mahabharata. On the battlefield of Kurukshetra, Krishna gives the famed warrior Arjuna a series of teachings, and it is obvious that Krishna is no mere mortal. Arjuna begs for Krishna to reveal His true form. Krishna complies and gives Arjuna the spiritual vision which enables him to see Krishna in His true form, a magnificent and awe-inspiring manifestation, containing everything in the universe; a description of this theophany forms the main part of Chapter XI.
Hinduism is based on the concept of one all-embracing supreme spirit known as Nirguna Brahman, that is, Brahman without form. This contrasts with the appearance of God in various physical forms, or avatars, which are then known as Saguna Brahman, i.e., God with form.) Nirguna Brahman is the first spirit, with slight similarities to the Judaic/Christian God before the creation of the universe, although Brahman is taught to be both the essence of being in the world as well as its material body. Nirguna Brahman thereafter is referred to as three different supreme manifestations according to their current activity. In the creation of all that exists, it is known as Brahma, the Creator. In the maintenance and development of existence, it is known as Vishnu, the Maintainer. And in the end, when the Great Spirit gathers everything back into itself, it is known as Shiva, the Destroyer.
The Shiva aspect of the Great Spirit was paraphrased by Robert Oppenheimer upon witnessing the first atomic bomb test, "Now I am become Death, the destroyer of worlds."
Only the Maintainer Vishnu aspect of the Great Spirit is considered to be currently active. Vishnu sometimes manifests Himself as a human for purposes of setting mankind back on the path toward spiritual perfection that will allow mankind and all of existence to reunite eventually with the Great Spirit Nirguna Brahman.
Other Hindu theophanies include Swami Vivekananda's experience of cosmic consciousness and a merging with the Nirguna Brahman when touched by the Hindu master Ramakrishna Paramahansa.
Read more about this topic: Theophany