Gnosticism refers to a group of religious movements that developed in the second century and claimed to follow Christ. The word comes from the Greek γνῶσις, “knowledge”. Its followers taught that salvation comes through hidden knowledge, reserved for a few initiates. The Church Fathers judged them heretical, and it was in answering them that the Church clarified its faith.
One label for several systems
As the historian Roger Olson points out, “Gnosticism” is a generic label: there was no single Gnostic doctrine, but several systems. They did, however, share a few common features:
- Dualism: spirit is divine, matter is evil. The material world is seen as a prison.
- A purely spiritual Christ: he is a messenger sent by an unknown God to free the divine sparks trapped in human bodies. He did not truly take on flesh.
- Secret knowledge: salvation comes through hidden knowledge, passed on by supposed secret apostolic traditions.
The New Testament says the opposite: “the Word became flesh” (John 1:14). The Christ of the apostles has a real body.
Why it was dangerous
The Gnostics were not outside opponents, like the pagan philosopher Celsus. They called themselves Christians, so they could unsettle believers from within. Many were drawn to the idea of a “higher” and “more spiritual” truth than the one preached to the crowds. Yet the gospel of Jesus and the apostles was a simple message, proclaimed to everyone in the same way.
How the Church responded
Irenaeus of Lyon wrote his work Against Heresies mainly to answer the Gnostics. His argument is about sources: their system, he writes, “neither did the prophets announce, nor did the Lord teach, nor did the apostles hand down”. Against secret traditions, he sets a public tradition: in every major Church, the list of bishops going back to the apostles can be named. He also formulated the rule of faith, a summary of the gospel that every candidate for baptism learned by heart.
According to Bruce Metzger, Gnosticism and the other crises of the second century forced the Church to define its faith more clearly, to say which writings carried authority against the secret gospels, and to affirm the value of the Old Testament. Paradoxically, heresy became one of the driving forces behind the clarification of Christian belief and the shaping of the canon.