Sean Martin’s The Gnostics: The First Christian Heretics (Pocket Essential series) provides a concise overview of the early Gnostic sects that flourished alongside mainstream Christianity until being largely suppressed by the 6th century. The book details how Gnostics, unlike orthodox Christians, prioritized direct inner knowledge (gnosis) over dogma, believed the material world was created by a flawed lesser deity, and held women as equals, offering a comprehensive look at their traditions, beliefs, and lasting influence.