Gnosticism was considered a heresy among the early Christians and persisted for many centuries. Drawing upon the latest scholarship and a wide range of sources, including the writings of the Gnostics themselves, Giovanni Filoramo provides an introduction to this variation of early Christian dogma. He traces the origins and history of Gnosticism, from its beginning in the first two centuries AD, and the development of Gnostic beliefs and mystic philosophy. He aims to demonstrate the links between Gnosticism and heretical movements of early medieval Europe.