Charlemagne and his family was responsible for a Christian empire because when Charlemagne was first battling he was taking over the Saxons, he killed all the people that didn't convert to Christianity, and when he became king the holy roman empire he united it into a christian kingdom.
Charlemagne's kingdom became the holy roman empire when he converted everybody to Christianity, plus he was given the name GREAT because he did a lot of great things.
Charlemagne improved the legal system by making it so you don't have to bur your hand,almost drown, etc. to prove your innocence. when Charlemagne took over he made it so everyone, peasants and nobles alike where given an equal right
Charlemagne thought it was right for a king to read and write because he wanted to effectively convert people to Christianity. Plus, Charlemagne wanted his officials to read and write
Charlemagne wanted scholars to copy down old manuscripts to preserve much knowledge. Plus all books were written to glorify religion, and during this time period religion was the most important thing