Gnosticism (from gnostikos, "learned", from Greek:gnōsis, knowledge) is a modern scholarly term for a set of religious beliefs and spiritual practices found among some of the early Christian groups called "gnostic" ("learned") by Irenaeus and other early Christian heresiologists.

The term also has reference to parallels and possible pre-Christian influences of the Christian gnostics.The base of discussion of gnosticism changed radically with the discovery of the Nag Hammadi library, and led to revision of older assumptions, and a reorientation of modern scholarship following the 1966 conference on gnosticism in Messina.