My feeling has been that Lori has always been of a sane mind (perhaps with some personality or mental disorder(s), but with a hold on rationality). She used these cult beliefs as useful cover to play out her dark, self-possessed agenda. She used cult beliefs to her advantage among those she thought would be sympathetic (MG, for example) and discarded them when the audience changed (Gilbert police, for example). I don't see her as a true believer (believer of convenience, maybe).
So now that the audience is a judge/jury, she is playing the insanity card. It seems to me she is using insanity as a state of mind that she can fluidly, strategically inhabit or discard depending on the circumstance.
What she and Chad did, though riddled with flaws, was stone-cold calculated and entirely tethered to the real world of LEO evasion, insurance fraud and cover up.
All JMO