Information from https://en.wikipedia.org/wiki/Henotheism
Henotheism is the worship of a single, supreme god that does not deny the existence or possible existence of other deities that may be worshipped. Friedrich Schelling (1775–1854) coined the word, and Friedrich Welcker (1784–1868) used it to depict primitive monotheism among ancient Greeks.
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Henotheism was the term used by scholars such as Max Müller to describe the theology of Vedic religion. Müller noted that the hymns of the Rigveda, the oldest scripture of Hinduism, mention many deities, but praises them successively as the “one ultimate, supreme God”, alternatively as “one supreme Goddess”, thereby asserting that the essence of the deities was unitary (ekam), and the deities were nothing but pluralistic manifestations of the same concept of the divine (God).
The Vedic era conceptualization of the divine or the One, states Jeaneane Fowler, is more abstract than a monotheistic God, it is the Reality behind and of the phenomenal universe. The Vedic hymns treat it as “limitless, indescribable, absolute principle”, thus the Vedic divine is something of a panentheism rather than simple henotheism. In late Vedic era, around the start of Upanishadic age (~800 BCE), theosophical speculations emerge that develop concepts which scholars variously call nondualism or monism, as well as forms of non-theism and pantheism. An example of the questioning of the concept of God, in addition to henotheistic hymns found therein, are in later portions of the Rigveda, such as the Nasadiya Sukta. Hinduism calls the metaphysical absolute concept as Brahman, incorporating within it the transcendent and immanent reality. Different schools of thought interpret Brahman as either personal, impersonal or transpersonal. Ishwar Chandra Sharma describes it as “Absolute Reality, beyond all dualities of existence and non-existence, light and darkness, and of time, space and cause.”