Thought Experiment Time: What if Rome never fell?

[Chan790]

3. Roman Paganism was dying anyways.

Christianity filled a void in an increasingly cosmopolitan agnostic society...it's likely that if Christianity had not filled this void in the 4^th century CE that Islam would have filled it by the 6^th century CE with the primary oppositional faith being the Druidic naturalism of the Celts and Picts and a larger agnostic bloc. The Romans in Brittania never really snuffed out the native faith, that was Saint Patrick in the 7^th century CE.

Everything else falls in from there.