A Gnostic is someone who follows Gnosticism, a diverse set of ancient religious philosophies emphasizing salvation through secret, intuitive spiritual knowledge (gnosis) rather than faith or works, believing the material world is a flawed creation by a lesser deity (Demiurge), trapping divine sparks within humanity, from which one escapes by awakening to the true, transcendent God.
Gnosticism flourished in the early centuries CE, borrowing from Christianity but diverging significantly, focusing on spiritual liberation from this material prison.