We just learned about the Protestant Reformation.
Another part of early Christianity was the French Wars of Religion.
In the 1500s, the Catholic church and another group of Christians called Huguenots fought each other for over 30 years.
It was a very bad war, and about 3 million people died.
The Huguenots and the Catholics just did not agree on what the Bible said was the right way to believe, and because there were princes, kings and queens fighting about this it turned into a war.
Because the war was so bad, a lot of people from around the world started looking at Catholics as not very nice, and other people joined the protestant reformation.
(from: wikipedia - french wars of religion)
Kid Facts - Blast from the past: Icons