The Nag Hammadi codices are easily the second most important discovery of the early Christian era, rivaled only by the Dead Sea Scrolls1. They were discovered buried in the sands of the Nag Hammadi region of Upper Egypt in December, 1945, by a pair of Bedouins who were digging up nitrates with which to fertilize their fields. They suffered extensive damage as they were separated, traded, sold, and in the case of one codex, burned, by Bedouins who didn't know their value. Eventually, the codices found their way into the hands of antiquities dealers who understood their significance, and from there were acquired by the Egyptian Department of Antiquities. Today the entire collection rests in Cairo's Coptic Museum.
What They Are
A codex is an ancient form of a bound book, in this case stacks of papyrus sheets folded down the middle and bound together. There are 12 codices in all, plus eight leaves from a 13th found tucked inside another. These contain a total of 52 tractates2, all written in Coptic, which is simply the Egyptian language written down with Greek characters.
The tractates represent a broad range of material, taken from different authors, from different time periods, and different viewpoints. An excerpt from Plato's Republic, at first glance, seems oddly misplaced with Hermetic (relating to ancient occults) discourses and apocryphal Christian texts. Through further study, a pattern begins to emerge. The collection represents the philosophy and ideals of Gnosticism, one of the very first Christian heresies. So early, in fact, that oblique references to it exist in the New Testament.
With the discovery came a chance to learn about ancient Gnosticism from sources other than mainstream Christianity, and hear their views from their own mouth, as it were. Gnosticism was a dualistic belief system. They believed everything in the world was a battlefield for the forces of good, represented by God, against the forces of evil. They believed that the creation of Earth and man were the results of a cosmic catastrophe. God created the world as a boundary with evil, and evil invaded.
The animosity from the Church seems to be mutual, as one tractate contains quotes attributed to Jesus himself which criticize what eventually became mainstream Christianity. The core of the religion was a belief that salvation comes from insights into a secret knowledge. Gnostics believed that the Christian resurrection was already a spiritual reality, and this belief was the heart of the confrontation. When mainstream Christianity converted the Emperor Constantine, the fate of Gnoticism was sealed. By the 5th Century, Gnosticism was completely eradicated, with the sole exception of a small enclave in southern Iraq, called the Mandeans, who still survive today.
As mentioned before, the tractates cover a wide range of subjects, and come from a variety of sources. Some are difficult to attribute to Gnosticism, instead reflecting other mystery schools active at that time, such as Zoroastrianism3, Hermeticism4, and Neoplatonism5. However, the Gnostics were much more open-minded than their Christian brethren. So long as they could find concordance with the beliefs detailed in a tractate, they accepted it and incorporated it into their own.
Among the apocryphal Christian texts is the Gospel of Thomas, which, since its discovery, some churches have added to their canon. It is a collection of the sayings of Jesus, and appears to have been used as a source for the writers of the Four Gospels. Biblical scholars had long believed in the existence of a single source of Jesus's sayings, which they call 'Q'. The current consensus is that Thomas is not the original Q, but a copy of sorts once removed. Other notable Christian apocrypha are a letter to Phillip from Peter, gospels from Phillip and Mary Magdalene, and various apocalyptic books comparable to the book of Revelations, although their content differs widely from Revelations.