Sources: How Do We know about Gnosticism?

Key to the modern study of Gnosticism is the Coptic-language Nag Hammadi library discovered in 1945. A good number of these texts are gnostic writings, on the basis of which we can know more precisely what the gnostics themselves actually thought.

Many of the gnostic texts in the Nag Hammadi library stem from Sethian Gnosticism. As a matter of fact, the centrality of this branch in the history of Gnosticism and our awareness of its main doctrines are the direct result of the study of the Nag Hammadi texts. Another major part of the Nag Hammadi texts are Valentinian writings. The library thus confirms that Valentinian Gnosticism was one of the most important forms of Christian Gnosticism in the second and third centuries.

Prior to the discovery of the library, our knowledge of Gnosticism was largely confined to references by the Church Fathers and a few original documents. When the Church Fathers describe Gnosticism, they mainly present summaries of gnostic doctrines though they also include some direct quotations from the writings of gnostic teachers. The reason why the Church Fathers deal with Gnosticism is in order to condemn it as a Christian heresy. For this reason, their descriptions of Gnosticism are often hostile and tendentious, but that is not to say that they have lost their relevance for the study of Gnosticism after the discovery of the Nag Hammadi library. The texts found at Nag Hammadi have shown that, at least in certain cases, the Church Fathers used original gnostic sources.