Among the Greek papyri discovered at Oxyrhynchus were three fragments containing sayings of Jesus. It turned out that these formed part of a complete work, the gospel of Thomas, which in a Coptic text of about 350 CE was among the important writings found at Nag Hammadi in 1945. The original fragments had generated discussion about the history of the transmission of Jesus' sayings in the oral tradition. Then the publication of the 114 sayings of Jesus (without any narrative continuum) in the complete gospel stimulated lively scholarly controversy. Some of the sayings have close resemblances to those in the canonical synoptic gospels; others are quite different, of which five have been reliably claimed as authentic.
It is disputed whether the sayings resembling those in the canonical gospels come from an independent oral tradition (and therefore are perhaps closer to what Jesus in fact said) or whether they show knowledge of those gospels (and so must be later). The first view is taken by those who believe that the Thomas sayings represent a collection which is ‘very, very early’ and remarkably free of any ecclesiastical interests. On the other hand, Thomas is without doubt a Gnostic work. In that system Christ shares with true believers a secret knowledge (gnosis) which enables them to be liberated from the evils of this world. The sayings in Thomas conform to this system; it is the words which offer the means of salvation—not, as in mainstream Christianity, Jesus' death and resurrection. Jesus' term ‘Kingdom of God’ is used here in a different sense from that in the synoptists; it is not an external reality but refers to the innermost self of a person who has come down from heaven but has forgotten its origin.
Although some of Thomas' parallels with sayings in the canonical gospels are shorter, that is not a certain indication of being earlier and independent; after all, Matthew, following Mark, often abbreviated that gospel in order to accommodate more of his own special material. Evidence of Gnostic adaptation of Jesus' parables has been shown to be in such a way that they have become vehicles of esoteric Gnostic teaching. And the tradition which Thomas was adapting was probably not an oral tradition but the written canonical gospels, as indicated when one of the Greek fragments from Oxyrhynchus presupposes Luke 8: 17, which has altered Mark 4: 22.
It would seem that Thomas is not a ‘fifth gospel’ offering an additional and faithful reproduction of Jesus' sayings, but a work designed for its own clientele with only a few sayings of Jesus of demonstrable authenticity.