Complex sentence: Therefore most of the negative stereotyping of the Irish is rooted in the politics of cuius regio, eius religio, a principle that held that every ruler had the right to dictate what religion their subjects should believe in.
Split into simpler sentences: Therefore most of the negative stereotyping of the Irish is rooted in the politics of cuius regio, eius religio. A principle which held that every ruler had the right to dictate what religion their subjects should believe in.