Well, since most audience here are non-Chinese speaking people, how about let's be clear. So in this context, "神马／神么" are Mandarin words, and I believe that people in HK speak Cantonese and don't usually use these Mandarin words.
On the other hand, IMHO, just IMHO, "God" being translated into Chinese(Cantonese) as "神" is not thoughtful as it introduces confusion.
Literally, "神" doesn't mean "God", "God" in Chinese is "上帝".
I'm a native Chinese.