Unoficial forum guidelines

Ok, not sure this is a wise decision or not, but... What are the unofficial forum guidelines, and where do i find them? Do i have to figure them out by myself? and how can i possible know what i am allowed post about or not? We cannot discuss religion, yet i don't find those restrictions listed in the forum guidelines. It's probably just be me being dumb, but could someone please point me in the right direction?