the.com/gnosticism

means An umbrella term for ancient religious movements holding that salvation comes through special inner knowledge (gnosis) of a divine spark trapped within, rather than through faith, law, or ritual alone.

from From Greek 'gnōsis,' meaning knowledge — specifically the personal, intuitive, know-it-in-your-bones kind, as opposed to 'episteme,' systematic or scientific knowledge. The '-ism' was tacked on much later, in the 17th-18th centuries, by scholars and heresiologists cataloguing the scattered sects — Valentinians, Sethians, and others — that early Christian writers had condemned centuries earlier as heretical. So the word is really a retrospective label: the ancients who held these beliefs didn't call themselves 'Gnostics' as a unified movement; that tidy category was assembled afterward by their critics and, later, their historians.