I listed this book recently in a post about what I was reading and now I've finished it. The central thesis of the book is that Christianity by the fifth century, served to impede the advancement of science and eason and only began to break out of its lethargy during the time of Thomas Acquinas in the 13th century. Simply put, Christianity was a major contributor to the dark ages, more so than Christian historians would like to admit and most Christians understand.
I'll admit that I was skeptical of this position even before reading the book and had attributed the dark ages more to the collapse of the Roman empire and the resulting power and cultural vacuum it created than anything else. After reading the book I can see that the author had some valid points. His basic argument goes like this chronologically.
While I certainly don't agree with all of the above points, especially his almost obsessivley negative view of Paul and his secular view of Jesus, his argument does make a certain amount of sense. I don't think he puts enough emphasis on the fall of Rome and its consequences although he notes that the "barbarians" had largely been converted to Christianity by the time the empire dissolved. He also only develops his argument overtly in the second to last chapter and the epilogue. Much of the rest of the book is straight history (although with a little interpretation that serves his purposes to be sure).
I found especially interesting his discussion of the development of patron saints of various illnesses from pagan forerunners. As a protestant this always confused me and so to see an historical explanation was welcome. I also tend to accept his view that Constantine and other emperors were first politicians, only nominally Christian, who used Christianity for means other than personal salvation.
I would recommend this book for those wanting to look at the history of the early church although I would caution that the author's viewpoints are ultimately quite liberal.