Remember, heretics are the folks who abandoned your religion for another religion (or another seriously different version of the same religion).
As an example, today almost all Protestants are not heretics ~ that's because they were never Catholics. However, the first Protestants were heretics. Which is, of course, why they referred to themselves as "Reformers". Polite Catholics hoping to avoid armed conflict also referred to early Protestant heretics as "Reformers".
Later on war happened anyway ~ Germany was nearly exterminated ~ Huguenots were murdered and driven to the far corners of the world ~ and finally the Treaty of Westphalia was signed and life went on as normal with the exception that Western European Christians quit calling each other heretics and they quit killing each other in the name of God (with the exception of the 17th Century when the Edict of Nantes was rescinded by the King of France and even more Huguenots poured out of France to go even further).
Non-Western European peoples have not yet learned this lesson.
We're using different definitions of heretic. We can talk later.
Silly