You know, Masshole Bambi Lydia seems like she's Christian because that's what good girls do, and she's a "good sweet girl". Alexis, however, seemed to be Christian because she truly believed. Both were sometimes offensive with their dogma, but at least with Alexis I felt like she was in it for the long haul.
Edit: I'm not casting aspersions, she could very well be a serious Christian. I just see her defining herself as the good girl and not embracing the fact that she's actually a Heather or Regina George deep down. Embrace it Lydia! You might be more palatable.