There are some kinds of Christianity that insist you have to believe literally in doctrine. The Gnostic gospels open out the complexity and multiplicity of approaches to this. If you think the story of the virgin birth is mistranslated, for instance, it doesn't mean you have to throw out the whole thing.
The Gospel of Judas really has been a surprise in many ways. For one thing, there's no other text that suggests that Judas Iscariot was an intimate, trusted disciple, one to whom Jesus revealed the secrets of the kingdom, and that conversely, the other disciples were misunderstanding what he meant by the gospel.