I personally think the belief of a God being much greater than previously deified emperors likely changed the perspective and mentality of the empire and subsequently led to its eventual collapse. I'm not well versed on the fall of the empire and have yet to read Gibbon, but I know many of you are and have. What are your opinions/claims?
Gibbon's view on the correlation between the rise of Christianity and the collapse of the Roman Empire in the west is very outdated. I don't believe there are any credible modern historians who share that belief. The easiest argument against it is that in the fifth century it was only the western half of the Roman Empire that collapsed, and the western Roman Empire was much more pagan than the east. The Senate in Rome remained heavily pagan for a long time, while the eastern half of the Roman Empire was more heavily Christian. Therefore, if Christianity was to blame for the collapse, it should have been the eastern Empire that collapsed. This is just the easiest example to explain from my phone, there are many more flaws in the correlation.