The main goal of Saint Irenaeus’s Against Heresies was to counteract Christian teachings he believed to be false and insidious. Most of those doctrines fell under the category of Gnosticism, a second century Christian movement that emphasized knowledge (from the Greek word gnosis) as the key to salvation. Irenaeus set out not only to show the absurdity of the Gnostic systems but also to warn against the ethical dangers of such systems. He did so in five books addressed to an anonymous reader.
Book 1 is largely a catalog of various heresies. Foremost among these is Valentinianism, a movement begun by Valentinus, a prominent Christian teacher in Rome in the middle of the second century. He expounded an elaborate cosmology in which the creator of the world was evil and thus all material things—including human bodies—were also evil. Those people who realized that they were spiritual and not material (including Valentinus and his followers) were the only ones who would experience salvation; the others (the majority of Christians) had an incomplete understanding of the truth. Irenaeus’s argument against the Valentinians takes two directions. First, he shows that the Valentinians pervert Scripture by taking it out of context and ignoring the plain sense of the text. Second, and more important, he argues that the Valentianian system attacks the unity of the church. Irenaeus emphasizes that the church must stand as a whole, “as if she had but one soul and heart.” Valentinians, however, extol individuality. Irenaeus’s stress on the unity of the church is the most prominent polemical aspect of the entire work. The rest of book 1 is a long catalog of other prominent Christian heresies, each of which Irenaeus describes and then attacks.
In book 2, Irenaeus elaborates on many of the points he made in the first book, arranging his discussion under theological topics. He confines himself primarily to the Valentinians, but he claims that the arguments against them are damning of other heresies. Irenaeus favors absolute monotheism over the polytheism of the Valentinians, stating that to believe in polytheism is...
(The entire section is 879 words.)