Against Heresies (Irenaeus)

Against Heresies (Koine Greek: Ἔλεγχος καὶ ἀνατροπὴ τῆς ψευδωνύμου γνώσεως, Elenchos kai anatropē tēs pseudōnymou gnōseōs, "Refutation and Overthrowal of Knowledge falsely so-called"), sometimes referred to by its Latin title 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 other schools of Christian thought, whose beliefs he rejects as heresy. He contrasts them with orthodox Christianity.