The first thing I have to say about the book is that the authors should have employed a good editor: it is incredibly repetitive. I think the message could have been got across in a book half the size. And now that's out of the way I'll tell you a little more about the contents.
The authors look at the church as it was in the New Testament and how it is now and how things have come to be done the way they are. A lot of the points they make are obvious but the historical explanations are fascinating. It seems we owe a lot of what is commonly thought of as religious ritual - that must be followed, of course - to Constantine (the Roman emperor who made Christianity the religion of choice in the third/fourth century) and all sorts of leading Christian characters through the centuries. For example the first church building was constructed by Constantine; the church referred to the NT is always a group of people, never a building.
Pastors, liturgy, choirs, tithing, Sunday school, steeples and spires, communion, they all get checked over - and are found wanting. It doesn't take a lot of reading of the book of Acts to see how very different the church was then but the point the authors make - and get very worked up about - is that all the ritual that has been added on to church simply serves to take away from what should be an every-person participating, mutually edifying living organism.
Some bits of the book are less interesting than others; some are based on little evidence; all is fascinating. A lot of it is less relevant to me as I don't belong to an Anglican or Roman Catholic church but thinking about a typical Sunday meeting in Linden it's not that dissimilar to the order of service laid down by Calvin and before him Luther, who in turn based his on the old mass.
That church isn't as it should be is evident from all sorts of reports of decline and scandal. Pagan Christianity suggests a return to what church was meant to be. I pray that at Zac's we can journey down that road a little further. (But stopping just before martyrdom preferably.)