The title of this article is ambiguous. For other meanings, see Gnosis (disambiguation).

Gnosis (from ancient Greek γνῶσις gnō̂sis "[er]knowledge" or knowledge) or gnosticism (Latinized form of Greek γνωστικισμός gnōstikismós) is a term used in religious studies to describe various religious doctrines and groupings of the 2nd and 3rd centuries AD, and in some cases earlier precursors.

The term is also used for various currents that are related to these groups in terms of their history of influence or that have similarities in the doctrines they advocate. Gnostic positions partly took root in some communities of early Christianity, but were strictly rejected by the New Testament, and gnosis developed into the main theological opponent of the early church in the 2nd century.

In spite of all differences the Gnostic teachings show a certain basic tendency: A supreme "good deity", which is above all earthly reality par excellence, unfolds in multiple gradations and outpourings (emanation). The visible world was created by a "demiurge", who also formed the inferior "carnal" man, by mixing the pneuma, which belongs to the divine upper world, with the "evil matter". The redemption of man lies in gnosis, that is, in the knowledge of his cosmic destiny and the divinity of his own self.