Lost Christianities by Bart Ehrman - History
It's really interesting, a book about the gospels and other books that didn't make the grade into the New Testament as we know it today and why not, even though they were popular at the time (roughly 100-300AD). Christianity sounds like it was chaotic in the early days with people believing all sorts of different things. Certainly could have been a lot more inclusive of different beliefs..,
I'd absolutely recommend but only if you're a history geek like me interested in this subject matter otherwise it'd be quite dry