Hmm. Like many mentioned she was just psychotic. The religious part was just the make up for the insanity.
I know some people believe in ghosts and stuff like that. But Ghosts/Angels/Devils would have been discovered already if they had an effect on our reality.
Such terms were used to explain things that were impossible to explain in the past. Mostly it has something yo do with altered perception of the world through hallucinogenic drugs like magic mushrooms which they put into the beer or other food or through mental illnesses that cause you to interprete stuff the wrong way. Because your brain messes up in putting action and reaction in the proper time frame or saves things in the wrong emotional context. This can even be influenced by other people or by yourself so that even rational people start believing weird stuff. Human minds can easily be influenced. Example If you are on a concert you can hate the music but if the crowd is having a lot fun you are too. If the whole world starts phantasising about Ghosts and everyone around you takes it seriously you will end up believing it too. If you grow up in an environment that seriously believes an alien robot sneaks into houses at christmas and determins if the inhabitants will have a good/bad/ok year ahead you will believe it. Some might be harder to convince but a couple of doctors some religious leaders pseudo scientific research and media coverage will convince most people.
Here we got a gullible person fed with weird informations and paired with a physichological condition that strengthens those believes and gives her the certainty that she is right and she acts accordingly.
Nothing to do with religion but you could argue that given a different background in the past she would have acted differently.