How do you say "Happy Sunday" in your own language ?
Here in Slovenia, Christian people also go to church every Sunday, but they never say "happy Sunday" (or "Vesela nedelja" in Slovenian) to each other. It sounds a bit weird in my opinion. =/
It is about religion Oliver.
Christian people usually go to the church on sunday. And they always say happy sunday to each other.
Хорошего воскресенья (Russian)
Bom domingo! (Portuguese)