I didn’t notice much of an anti Christian bias. Which is amusing since my antenna is rather hypersensitive on that issue.
The author’s thesis, namely, megatrends of demographics and disease led to the fall of the classical era despite good political and military leadership was legitimate. He reinforces Mark Steyn’s theory that demographics is destiny. China for example has withstood numerous foreign invaders and foreign rulers. All of which are eventually overthrown or absorbed by the massive Han gene pool.
Justinian was a wise and effective ruler but classical Rome was doomed despite him.