Irenaeus: Against Heresies

Irenaeus of Lyons wrote Against Heresies (Latin: Adversus Haereses), a foundational work of Christian theology around 180 AD, to combat Gnostic and other heretical movements threatening early Christianity. The text, composed in Greek, is structured in five books and serves as a comprehensive refutation of Gnostic doctrines, particularly those of Valentinus, whom Irenaeus identifies as a central figure in a broader network of heresies.