On the Detection and Overthrow of the So-Called Gnosis (Ancient Greek : Ἔλεγχος καὶ ἀνατροπὴ τῆς ψευδωνύμου γνώσεως), sometimes called Adversus Haereses, is a work of Christian theology written in Greek about the year 180 by Irenaeus, the bishop of Lugdunum (now Lyon in France). In it, Irenaeus identifies and describes several schools of gnosticism and contrasts their beliefs with his description of orthodox Christianity.