" What is the big deal when you say "good luck with that" or He just had bad luck? I have never been a JW, but what is the problem with saying these things? My husband was so mad, he went to bed and would not talk to me. ?????"
Besides his JW understanding that "Luck" is a belief in some ungodly outside force, there is sometimes a note of sarcasm that is implied when one used the expression "good luck with that ". Sometimes that expression implies your doubt in the other persons chances for success on their own and that "good luck" is their only hope. It's almost like saying "fat chance".
Husband: I'd like to invite my boss and all of my coworkers over for one of your famous home cooked dinners sometime.
Wife: Oh yeah?? Well good luck with that ! (fat chance !)
Maybe your husband felt you were doubting whatever it was you two were discussing at the moment and you were wishing him good luck as a way of telling him you weren't in agreement or weren't standing behind him.