One thing I really got out of the History of Rome podcast by Mike Duncan is if anyone tells you there was ONE cause of the fall of Rome, they're full of crap.
That's very reasonable. But there was a slow collapse of the economy that is an intermediate cause in the chain of events that is central to the fall. You can speculate what caused that collapse, that in turn caused the fall and there are also many causes to consider, but again, there is one intermediate cause that is Christianism. The religion altered several aspects of the economy: slavery, commerce and lending. No…
It does seem that the western half of the empire was more dependent on slavery. But Christianity wasn’t the only factor in that. With fewer conquests there were fewer slaves to take.