Documented twice: the complete Coptic text from Nag Hammadi Codex II, and three Greek fragments from Oxyrhynchus (P.Oxy. 1, 654, 655) excavated from an Egyptian rubbish heap in 1897-1903, dated to the early third century. The Greek fragments prove the sayings circulated centuries before the Coptic codex; composition estimates run from the mid-first to the second century.
The scholarly frame: Thomas is a sayings gospel, the same genre as the hypothetical Q source reconstructed behind Matthew and Luke, and roughly half its sayings have synoptic parallels while half are unique. Whether it preserves independent early tradition or mines the gospels is the field's longest-running argument, with credentialed scholars on both sides since 1959.
The text's documented theology: no apocalypse, the kingdom is spread out upon the earth and people do not see it, salvation through interpretation, not atonement. For the tradition that canonized the cross, Thomas was unusable; for the Nag Hammadi community, it was the master text. The canon decision is itself the archive's exhibit.
Is this the oldest Jesus we have, or a second-century remix?