Where does a religious joke start?

Is a joke starting with "A man and his wife" anti-islamic, because the "his wife" implies that there is only one wife?

Or "On his free Sunday ..." anti-jewish, as for Jews, the Sabbath (spelling?) is the usual free day.

A joke mentioning killing a cow then is anti-hinduistic and so on.

If you think about it, you might find there are no jokes left which you can legally tell ...