Leo Africanus Reading 3

This weeks reading of Leo Africanus brought some important aspects only obtained through first hand account. Leo is cast out for two years due to Hassan's the Ferret murderous act. This allows Leo time to go to Egypt, more particularly Cario where he left a house to watch over. He quickly finds himself adapting to the way of life. He encounters his up and downs along the way. He eventually is taken to Italy in which he officially changes his name to Leo. He was captured by the Christian pirates and is taken to the Pope and presented as a lavish slave so to speak. The pope and Leo become close and have many discussions.
One item of discussion that i find particularly interesting in the incorporation of religion and state. I guess it is very much related to technological advances, but at the time they felt the plague was caused by the "Most High." Today we know that the disease is cause by a virus. Also how religion was used to incorporate conquests known as "Holy Wars." Again, today if a country like USA were to declare war supporting religious conquest as it goal, we would have utter chaos,yet the states or Monarch's governing convinced millions to do so. It still amazes me to see the depth that religion is tied into how the state governs over the people. They seem to utilize it as a strategic tool of governing rather than a omniscient being. My question to everyone is, what steps or changes occurred for split of religion and state?