I think, sometimes its hard for people without religious belief to understand the view of those with religious belief.
I don't understand such things myself, though I keep the crude jokes with the crude peoples (there are certain things I will not say infront of women, for example, but I site that to my personal law of chivalry)
Some people don't understand jokes like that really hurt or offend people, mostly because they've never come across anyone who was offended/hurt by them.
(A family of athiests aren't exactly going to mingle with church goers, I don't know any religious people, for example).
And I think, some wouldn't know how to react... that's what I think, anyways, from a more outsider prospective.