What is the main idea behind the separation of church and state?

A.
Each country has the right to determine for itself if it will have a national religion.
B.
The government does not have the right to prosecute followers of Protestant religions.
C.
Each country, by law, has to declare one form of religion as the national religion.
D.
The government cannot dictate what religion is practiced by its people.

D. The government cannot dictate what religion is practiced by its people.