Stephen J. Patterson: While the cumulative nature of the sayings collection understandably makes the Gospel of Thomas difficult to date with precision, several factors weigh in favor of a date well before the end of the first century: the way in which Thomas appeals to the authority of particular prominent figures (Thomas, James) against the competing claims of others (Peter, Matthew); in genre, the sayings collection, which seems to have declined in importance after the emergence of the more biographical and dialogical forms near the end of the first century; and its primitive christology, which seems to presuppose a theological climate even more primitive than the later stages of the synoptic sayings gospel, Q.
Together these factors suggest a date for Thomas in the vicinity of 70-80 C.E. As for its provenance, while it is possible, even likely, that an early version of this collection associated with James circulated in the environs of Jerusalem, the Gospel of Thomas in more or less its present state comes from eastern Syria, where the popularity of the apostle Thomas (Judas Didymos Thomas) is well attested.