It's hard to find a book that doesn't have an agenda. Like the book Saints. It obviously has an agenda, seen by anyone with an actual knowledge of the history. That's why if you're really interested in a subject it's pertinent to read more than ones own side/apologetics. Imo.
Reading the review section on Amazon of various books is funny cuz a lot of them are basically: This book disagrees with the worldview and paradigm I was taught during my developmental years and so it's wrong and I disagree with it and don't like it.