User blog comment:Jazon Naparleon/Questions of Romans and Mongols/@comment-1630894-20120816211921

For 3, I don't think that Caesarion could raise any army in India capable of travelling to Rome and taking it.

For 4, I've heard people claim that the Roman Empire would have lasted longer or shorter without Christianity. To me, it really appears that their fall was inevitable, the series of civil wars, Germanic and Hunnic invasions, and the bad economic conditions had already happened and would continue to happen regardless of Christianity, but I don't think they would fall that fast even if Christianity did play a factor. I doubt they would have fallen more than a century earlier or later than OTL.