I read in the paper today that they've translated a Gospel of Judas. Christians will reject it, but why is it any less valid than the other gospels?

Okay, that's an rhetorical question. What I should probably say is that for someone outside of the Christian faith, why is this particular gospel going to be rejected outright while others are perfectly good and welcomed into the Canon? My mother refuses to believe that there were ever other gospels other than what is included in the Kings James version of The Bible. So if it's historical fact that early church leaders chose which gospels to include in The Bible and rejected others, why are we to accept that the people who made those decisions had the authority to do so? Are we to accept that certain gospels are not relevant simply because they said so?

With that in mind, I ask again. Why not this gospel? From what I understand, it doesn't actually contradict anything in The Bible. It does not claim that Judas did not betray Jesus, but claims that he did. The only difference is that it explains why he did that.

Look, I understand that there were a lot of fanciful gospels floating around at the time the early church assembled The Bible, and that this “gospel of Judas” was never a serious contender for inclusion. But to someone outside of the Christian faith, this may all seem like semantics. To someone outside of the faith, it's all fanciful tales.

In short, why not the Gospel of Judas?