Ebook: The Scandal of the Incarnation: Irenaeus Against the Heresies

On the Detection & Overthrow of the So-Called Gnosis, aka On the Detection & Overthrow of Knowledge Falsely So Called (ἔλεγχος και άνατροπή της ψευδωνύμου γνώσεως) or, in Latin, Adversus haereses, are five volumes written by Irenaeus of Lyons. The phrase "of knowledge falsely so-called" is from Paul in 1 Tim. 6:20. Due to an assertion that Eleutherus was current bishop of Rome, it's dated c. 180-188. The work's important as its dating is clear & it's amongst the earliest uncontroversial documentations for many Pauline letters & Jesus sayings.
Irenaeus describes several gnostic groups, contrasting their beliefs to what he sees as catholic orthodoxy. Fragments of an early Greek text exist, but a complete copy exists in a wooden Latin translation, made shortly after Greek publication. Books 4-5 are also present in a literal Armenian translation. Until the Nag Hammadi discovery in 1945, Against Heresies may have been the best surviving contemporary description of gnosticism.
Against Heresies refutes gnostic teachings. Some Greek merchants had begun an oratorial campaign praising gnostic pursuits in the bishopric. Apparently some Valentinian gnostics remained in the early Church, taking part in celebrations. They'd also meet privately to discuss secret knowledge & pertinent scripture. Bishop Irenaeus felt obligated to study them & become informed of gnostic doctrines. A main reason he did this was because he felt Asian & Phrygian Christians needed protection from gnostics because they'd few bishops. Due to the distance between him in Gaul & Asian Christians, he believed writing a treatise would be a good way to give guidance.