My first pass at this strip had a bit where Dorothy, who's not as religiously-marinated as Joyce, tries to do Christanity-themed double entendres but isn't good at them, while Joyce playfully admonishes her. I still really like this idea, but I didn't have enough panel space to make it work to my satisfaction.
(there's also the issue of trying to come up with Christianity-coded double entendres that AREN'T actually already a genuine, existing phrase is.... nearly impossible, you're gonna pratfall into a real phrase by default, really)
Pass 2 had two beat panels I really liked: 1) the fourth panel with Dorothy and Joyce with restrained, goofy faces, and 2) a final panel of an unaffected Mary refusing to respond to any of this. I wrote "MARY" over Mary's face in panel 1 because I wanted to see how my wife felt about the rhythm of it without me having to actually draw out Mary so she knew it was Mary. She felt so-so about this version.
The published strip takes some from both versions: the Joyce/Dorothy beat panel and Mary's response.