why are bad words bad words?

I once red that protestant countries use bad words connected to devils, hell and so on. And almost none with sexual content.Catholic countries tend to use sexual words or the holy mother. In Italy they say thing like "I will piss on your mothers grave" and so on. Since USA is a mix of both, they use both i guess. And through globalization bad words are getting mixed together much more nowadays.In sweden (protestant) all bad words are about heaven and hell. Just now recently you can hear people curse with words like cunt, f*ck and so on. It sounded relly weird just a couple of yrs ago though.What is the curses in muslim countries? Pigs and family ?
And in asian ?

Depends what you will use it for. If you just got hurt and are in pain, you just want to say something quickly to relive you of anger and pain. Then a short word is perfect.If you are to insult someone, I think longer words or even sentences have a better effect!