'Well, we're all Catholics.'
I need some help with the part of the film where Len's and Fay's friends and family gather at their house to help in the building of a nursery for the child they're expecting. My confusion begins shortly after a sudden rain shower forces everyone inside and into the kitchen where they continue the party. The talk turns to the soon-to-be-born baby, and Amy jokes that the narrow interval between Len and Fay's wedding and Fay's pregnancy is "what happens when you marry a good Catholic."
To this, Fay says, "Well, we're all Catholics, Amy. Everyone in this room's a Catholic. Len and I are what you'd call Roman Catholic."
The kitchen then goes quiet and everyone looks uncomfortable.
Obviously an insult was delivered here, but I can't figure out what it was.