I'm not completely sure, but I believe Barbara Hall was a Buddhist. and Joan of Arcadia was extremely generic about who "God" was. I don't think this was so much political correctness as much as a more universalist mindset.
I don't recall any mention of Jesus specifically, however, I believe there might have been an allusion to a Son in dialog of an episode, but I couldn't tell you which one.
You might find a Bible study based on the two season's of Joan of Arcadia by searching either the Presebyterian or Methodist church (Google it). I think you can buy it online from one of them. It was created by one of there Sunday School directors.
Post any cool information you find!