Bernadette IS presented as a Catholic character (one more thing for her Dad to disapprove about Howard-who is Jewish). She DID wear a cross, but now sports a star (that Howard brought along on this astronaut stint in the SpaceStation). The star www mentioned in an episode.
I really enjoy TBBT...the writing is smart and the characters are so quirky...I love that smart, nice Bernadette has a temper and that Penny is afraid of it!
Even Bernadette’s boss (Stephen Root) is afraid of her. That’s why he hires the unqualified Penny.