Maybe this is a strange question to discuss on a Porn forum... but do you think Mr. Palmer had planned out the religious beliefs of Anna Parker in the story? I wonder if Mr. Palmer had intended Anna to be Jewish.
There are a few clues, but nothing specific. On at least two occasions Anna says "Oy vey" which is a Yiddish expression. The religious building the flashback with Mr. Grant Stenstromber happened in could be both a Synagogue or a Church, with the exception of an Eastern Orthodox church (there should be no seating). No cross or star of David or other religious symbols are displayed IIRC. Anna is not wearing any head covering which would fit with Reform Judaism and most Christian denominations (not Eastern Orthodox, there women are covered in Church). Anna has the same hair at home and at work as well as before she was married so if Jewish, she is likely not Orthodox.
Later we see the flashback to Anna's childhood home, first the discussion between Elias and Grant, and then the scene with Grant and Anna in her room. I did not spot any religious iconography in that scene. And how about any clues with regards to male circumcision? I don't think we ever see David fully nude. Chris, who by name is likely not Jewish, appears to be circumcised which Anna does not comment on.
Food: Anna prepares and eats non-kosher food (pepperoni pizza, meat with cream sauce), but that does not mean much if she is not very observant of religious rules.
tl;dr: In conclusion, there is nothing solid to go on. The "Oy vey" may just be an expression used by the author without considering the perception by the reader. DAZ3 assets may explain the rest.