Heresy in general refers to a doctrinal belief held in opposition to the recognized standards of an established system of thought. Theologically it means an opinion at variance with the authorized teachings of any church, notably the Christian, and especially when this promotes separation from the main body of faithful believers. By the time Irenaeus wrote Against the Heresies the word became fixed to designate a group cut off from the Church by reason of false doctrine. From apostolic times the church claimed authority to safeguard the deposit of faith handed down from Christ and consequently condemned what were considered substantial deviation from Christian orthodoxy. In the sub-apostolic age and before the year 200, there were fewer than forty distinct sects, usually named after their founder or leading exponent, which are branded heretical by Christian writers. Irenaeus attacks at least fifteen, mostly of Gnostic origin, that were current in his day.Irenaeus Against the Heresies contains a profound exposition of Gnosticism and other heresies. In refuting heterodox systems he gives important testimony regarding the common beliefs of the early Christian Church. He writes: The Church, though dispersed through the whole world, even to the ends of the earth, has received from the Apostles and their disciples this faith He then records Catholic belief in the genuineness of the Gospels, in the Real Presence, and in a certain pre-eminence of the Church of Rome, the precise nature of which can be determined only from the whole context of Irenaeus writings.In Irenaeus Against the Heresies his principal attack is against the Valentinian Gnostics, whose myths shifted away from creation to Epistemology, examining how we know things, which he mocks as completely implausible. Irenaeus also attacks, non-Valentinian, heretics, but in a somewhat less sophisticated way. Gnosticism is a religious movement that attempted to reconcile a number of con...
