My thesis is that Christianity was heavily politicised by the late Roman empire, certainly to the extent that it would have been unrecognisable to Jesus. Note the linking of the church to the empire’s success in war, opulent church building and an ever narrowing definition of what beliefs one had to hold to be saved. (Hand in hand with this went an elaboration of the horrors of hell, a radical and unhappy development which can only have discouraged freedom of thought.) My core argument is that one result of the combination of the forces of authority (the empire) and faith (the church) was a stifling of a sophisticated tradition of intellectual thought which had stretched back over nearly a thousand years and which relied strongly on the use of the reasoning mind.
I did not depend on Gibbon. I do not agree with him that intellectual thought in the early Christian centuries was dead and I believe that the well established hierarchy of the church strengthened not undermined the empire. After all it was the church which survived the collapse of the western empire. Of course, Gibbon writes so eloquently that I could not resist quoting from him at times but my argument is developed independently of him and draws on both primary sources and recent scholarship.
On the relationship between Christianity and philosophy I argue that there were two major strands of Greek philosophy , those of Plato and Aristotle. The early church did not reject Greek philosophy but drew heavily on Platonism to the exclusion of Aristotle. [*] In the thirteenth century Christianity was reinvigorated by the adoption of Aristotelianism , notably by Thomas Aquinas. It seems clear that Christianity needed injections of pagan philosophy to maintain its vitality and a new era in Christian intellectual life was now possible. I don’t explore it in this book. Even so, when one compares the rich and broad intellectual achievements of the `pagan’ Greek centuries with those of the Middle Ages, it is hard to make a comparison in favour of the latter. Where are the great names? (The critic who mentioned the ninth century philosopher Erigena should also have mentioned that he was condemned as a heretic.)

* Consider the role of Plato’s philosophy in the origins of 20th century totalitarianism — the thesis put forth in Karl Popper’s The Open Society and Its Enemies.