Philip Jenkins explains:
On average, the Biblical world sees a startling new discovery of allegedly cosmic significance every four or five years. Most recently, we had Jesus’s Wife, with the Gospel of Judas not long before that, and no great powers of prophecy are needed to tell that other similar finds will shortly be upon us.
In themselves, the finds are usually interesting (if they happen to be authentic), but where the media always go wrong in reporting them is in vastly exaggerating just how novel and ground-breaking they are.
So powerful are such claims, and so consistent, that it sometimes seems as if nobody before the 1970s (say) could have known about the multiple alternative Christianities that flourished in the first centuries of Christianity. Surely, we think, earlier generations could never have imagined the world revealed by such ancient texts as the Gospel of Thomas, and the Gnostic documents that turned up at Nag Hammadi. Lacking such evidence, how could older scholars have dreamed what we know to be true today: the vision of Jesus as a Zen-like mystic teacher, or perhaps a Buddhist-style enlightener, who expounded secret doctrines to leading female disciples, and who may even have been sexually involved with one or more of them? Today, for the first time, we hear the heretics speaking in their own voices!
But here’s the problem. Virtually nothing in that model would have surprised a reasonably well-informed reader in 1930, or even in 1900, never mind in later years. In order to make their finds more appealing, more marketable, scholars and journalists have to work systematically to obscure that earlier knowledge, to pretend that it never existed. In order to create the maximum impact, the media depend on a constructed amnesia, a wholly fictitious picture of the supposed ignorance of earlier decades.
Emphasis mine. Please do read it all.