I would tell her to not use anything smaller than a .40 caliber and to place the barrel above her ear, not against her temple.

--cure her? Well,first I would tell her not to listen to her God,then I would tell her to read "The Story of Thought:A Essential Guide to Western Philosophy"and "The God Delusion"and then tell her to go to the library an get the DVD " A History of Disbelief " and then hope that she makes the right decision. 

If she is hearing voices she should do some rudimentary research on Auditory hallucination to help her understand and pinpoint the cause.

If this is how she feels emotional I would suggest an antidepressant.

 I dunno about Canuck land, but in America, therapists are strongly discouraged from challenging religious notions as a first approach.  I've actually asked several therapists questions about how they treat people with very serious delusions that appear to be religiously caused.  The general approach is to begin with how the patient feels about his beliefs, and try to find one that stands out as particularly important.  

For someone who thought god wanted her to shoot herself, the first thing would be to find out how she felt about shooting herself.  If it became obvious that she was depressed and suicidal, a good therapist would try to root out the causes of the suicidal desires, not to challenge the word of god.  (Later, she would try to figure out a way to help the patient decide that god really didn't want her to kill herself... )  If she felt very scared and wanted badly to live, but felt like god was punishing her, or something like that, it would be all about finding an immediate loophole within the belief structure.  For instance, "See, you believe God says this about that and the other, so god won't mind if you and I talk this out thoroughly before you make your final decision."

To the best of my knowledge, very few cognitive therapists treat religious delusion as a unique kind of delusion.  They simply evaluate the depth and breadth of the delusion and then try to find ways to make immediate changes in behavior where necessary and to chip away at the corners until they find the loophole they need to make the patient question the delusion seriously.

The bottom line is that most people in therapy have an immediate problem.  Therapists tend to try to solve immediate problems expediently, and it's not usually expedient to try to destroy a patient's entire worldview.  Instead, they try to find cognitive dissonance that resonates emotionally with the patient and will cause them to rethink their actions with regard to the specific problem. 

Okay, but how would you determine which one it is?

Definitely not a first approach, from the therapists or social workers I've discussed the topic with. I know of one case where the difficulty was precisely that medication caused "God" to "go away". The patient didn't want to be on medication, because she found that she didn't have that disembodied voice to talk to, and it made her feel lonely.

In answer to the OP, obviously AiG is right: you'd need a full case history to help determine if it was anything from suicidal ideation given a religious context to something like a psychotic episode. You haven't really presented enough information for an ethically responsible clinician.

I'm pretty sure the criminal code doesn't have a specific clause in the suicide section, but allowing someone to kill themselves after they've announced their intention might be construed as "death that might have been prevented". I think any "proper means" are acceptable, though, so the specifics are most likely not criminal, but ethical. I'm not a lawyer, though, so grain of salt.

In America, if a patient expresses suicidal urges, health professionals are required to take action to prevent it.  For psychologists, priority #1 is preventing suicide.  After that danger has passed, they can delve into the deeper inner workings of a person's brain to see if they can fix a long term problem.   But in the scenario Pineapple gave, if the psychologist couldn't determine that the suicidal statement was a lie, or clinically solve the problem, she might be required (depending on the state, I believe) to force the patient to undergo psychiatric observation for a few days.  (That happened to a friend of mine a few years ago.  Spent 5 days in the loony bin after telling a nurse he wanted to commit suicide.)

 You mean... you trust the media to determine truth?

Kinda, I created this thought experiment to determine whether or not it was actually "obvious" that religion causes people to kill others or themselves.

I already went through my line of reasoning with it before I posted, and wanted to post it to get others.

You have a bit of a which-came-first problem, in that you don't know whether a religious culture effects an individual, or a collection of individuals with similar ideas create a religious culture (or both), so it would be extremely difficult to determine which one was the definitive cause of a specific individual's specific actions.

However, religion still sticks out as a fantastic excuse to do things that would otherwise be considered terrible. That's not to say nationalism doesn't provide an equivalent excuse, but that they are both forms of the same tribal them-and-us characterizing that preceeds destructive behaviour towards others.

So my suggestion is that religious thinking is part of how we separate ourselves culturally from other groups, and thus dehumanize each other. In the case of nationalism, the arbitrary boundaries exist in physical space, while with religious thought, there's a confusion between physical and conceptual space.

Maybe it's that confusion that creates a likeness to those experiencing a psychotic episode.