1) The popular press takes this discovery out of context. It has been long known by scholars and by those who study "heresies" that there was a belief that Judas was the greatest apostle, willing to sacrifice himself and his reputation for the greater good. What is new about the find of the Gospel of Judas, is that it is the first time we have an historical example of a whole gospel written down, that presents this view. The fact that this view was so well worked out tells us something about how Christianity developed out of Judaism.
2) In short, this is an interesting historical find, even if it is a third rate literary find. Imagine finding a missing history of the Republic of Rome, written Circa 70 BCE by a known "populare" recounting the lives of the Gracchi. Such a find would be of historical worth in its own right but it would also tell us something about the decline of the Republic and the forces that went into making the Principate. Similarly, the discovery of this document tells us a bit of the forces that made Chritianity.
Why not view it simply as an historical find? Religious people will not view it in that way but certainly we should be able to do so.
3) Even today there is little understanding of the vast social and cultural forces that circled the Mediterranean at the time of the great Roman Imperial project. Historically Christianity triumphed. That Christianity triumphed, and that one particular form of Christianity triumphed, was not inevitable. Studying these social and cultural forces rationally, and trying to determine their political and economic nature -- understanding their class content, etc -- is simply what historians should be doing. "The Gospel of Judas" is one more contribution to the study of history at a particular time and place.
4) It seems irrational, for leftists to be so irked about this discovery, simply because it has been taken up by popular and religious culture in ways that will lead to further irrationalities. Part of our job is education and self-education, and even these discoveries can be used to do so.
Jerry Monaco