Definition: Irenaeus was a second century bishop in Gaul and Christian theologian about whose personal details we know little. Irenaeus is significant in the history of early Christianity because he helped establish the canonical New Testament and provided a picture of one of Christianity's offshoots, Gnosticism.
Irenaeus described and wrote against Gnosticism, providing a picture that was of value historically, although documents from Nag Hammadi reveal Irenaeus' descriptions as inaccurate.
Irenaeus was an early defender of the four canonical Gospels, Matthew, Mark, Luke, and John.
We don't know exactly when Irenaeus was born or died. He is thought to have come from Asia from a Christian family. Irenaeus is accepted as a saint in both the Roman and Eastern churches.
Two Latin works of Irenaeus have survived: Adversus Haereses ("Against Heresies") and "On the Subject of Knowledge."
