I will not pretend to have exhaustively studied it, but have not seen even references reliably dated beyond the late Second Century AD. Skimming the Wikipedia article on the subject turned up the following references:

Nicholas Perrin, "Thomas: The Fifth Gospel?," Journal of The Evangelical Theological Society 49 (March 2006): 66–80

Nicholas Perrin. Thomas and Tatian: The Relationship Between the Gospel of Thomas and the Diatessaron (Academia Biblica, 5). Koninklijke Brill NV, Leiden, The Netherlands: Brill Academic Publishers, 2003.

The first argues that, based on the second suggests, the "Gospel" of Thomas may have been recorded as late as 172 AD. If you have some ironclad proof it was around before then I would love to see it (as, no doubt, would Perrin.)


On the contrary, had Mormonism been around for a century and a half, perhaps more, before suddenly taking time to denounce previously unattested Roman Catholicism, I think that would be a valid objection to the latter. If we had some positive or even nocommital references to it from the same date, especially if they referred to it as an earlier work, that would be different. Instead, it was not even mentioned until the Christian Church had been around for a century, and likely much more, and all we have then is a categorical denunciation. It is more like if the Book of Mormon and related documents had never been written, but someone came along 20 years ago to say the whole thing was a bunch of hooey: Would that validate Joseph Smiths claims?


Yeah, those, too, certainly, but not only those. Gnosticism was just the Unitarianism of its day, recasting any and all divine revelation as metaphysical allegory. Trying to backdate their sacred texts to be products of existing religions, however, does kind of clinch things.