Wikipedia says that Budapest is home to one of the most populous Christian communities in Central Europe and it's considered to be one the most dirty places on Earth. Rome is often called Europe's dirtiest cities. Also Christian. Either Christ failed there, or religion has nothing to do with it.

One of the most dirty places on Earth. Surely this cannot be true. I’ve been to ten dirtier cities in India alone than that, let alone the rest of South and South East Asia. I suppose in some sense every city is one of the most dirty places on Earth even if you rank 500 on some list but it cannot be useful to think of it like this.