Why was Charlemagne a Christian emperor and what did he do to have that title?

Charlemagne, crowned as Emperor of the Romans in 800 AD by Pope Leo III, was a Christian emperor because he actively promoted and defended Christianity throughout his empire. He implemented policies that encouraged the conversion of pagan tribes, established schools that emphasized Christian teachings, and supported the church's authority. His reign marked a significant merging of Christian and political power, with the church playing a crucial role in legitimizing his rule. Through these actions, he became a symbol of the Christian faith in medieval Europe.