This is book on a fascinating topic, but it doesn't go quite far enough. As in his previous books, Jenkins explores the reality of Christianity in places and times that you didn't know enough about before. This time, he focuses on the apocryphal writings that were treated as Scripture in some contexts. This means he takes on Dan Brown and shows that, yes, there was a time when texts were suppressed, but it was only by a part of the church, and it was in the 16th century, not the 4th. Before the Reformation, non-canonical scriptures fluorished, and though they were certainly discouraged and persecuted, the fact of the matter is that the pre-modern state didn't have the ability to truly repress gospels it didn't like. Only with the advent of the printing press did such suppression become possible (which is a historical irony if ever I've seen one). The suppressor is not Constantinian -- he is Protestant!
To find out more about what this surprising statement means, you'll have to read the book. Unfortunately (I say with irony), Jenkins is a careful scholar, and so at times the book reads more like a card catalog than a thriller. Only in the final chapter does he really expand on the central thesis that these alternate Christianities and heresies, however fuzzy the line between them may be, are emblematic of the eternal variation and struggle in Christianity itself, and in every Christian's heart. This conclusion means that the history of the previous centuries can apply to us, today -- but Jenkins is cautious in his application, so those connections are mostly left up to the reader. So much thinking to do, so little time. Here Jenkins brings new treasures out of old storehouses, and the result is fascinating and even, in an odd way, encouraging. Dan Brown is nothing new.