Cesaropapism

Okay kiddo, so cesaropapism is a big word that means when a ruler or leader has control over religious affairs. See, back in the old days, sometimes rulers would want to have complete control over everything, including religion. So they would not let the priests or religious leaders have much say. They would even make decisions about how people should worship and what they should believe in.

This was different from how things should be, where religion and government should be separate and not mixed up with each other. That way, people could worship and believe however they wanted without any influence from the government or the ruler.

Basically, cesaropapism means that the ruler has too much power over religion, and that's not fair to people who want to follow their own beliefs. It's important to have a balance of power so that everyone can feel free to practice their religion without being told what to do by someone who is not a religious leader.