Irenaeus of Lyon

The heresy hunter who defined what counts as "real" Christianity.

Bishop of Lyon in Roman Gaul, Irenaeus wrote the massive five-volume "Against Heresies" (c. 180 CE), systematically cataloging and refuting every Gnostic Christian sect he could find. His work was instrumental in establishing the four-gospel canon and the concept of apostolic succession.

Verified Facts

• He is the first writer to explicitly argue that there must be exactly four gospels—no more, no less—comparing them to the four winds, the four corners of the earth, and the four living creatures in Ezekiel. This argument stuck.
• His concept of "apostolic succession" (that legitimate church authority can only come through an unbroken chain of bishops tracing back to the original apostles) became the foundational political claim of both the Catholic and Orthodox churches.
• As a student of Polycarp (who was a student of the Apostle John), Irenaeus represented a direct three-generation chain from the apostles to the institutional church of the late 2nd century.
• His detailed descriptions of Gnostic beliefs (which he wrote to refute) are ironically one of our best sources for understanding what the Gnostics actually believed, since most of their own texts were systematically destroyed.

Frequently Asked Questions

Sources & Further Reading

• Wikipedia: Irenaeus
• Wikipedia: Against Heresies

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