Why did Christianity play such a major factor in the fall of the Western Roman Empire?
Well, it was not exactly a major factor, but the way that the Roman Church began to gain influence and press for more crusades did tend to make some of their supporters waste a lot of money on those battles, money they were then required to extract from the peasantry…who began to be squeezed a little too hard, so expensive revolts began. Also the church was setting sympathetic rulers against any non-church-compliant ruler on a regular basis – excommunicating people right and left…it just exacerbated the situation where the empire had lost it’s role and the eastern invaders were really eating away at the eastern frontier.