What if its all just in your head?

Am reading a book that hypothesises that we are all genetically predisposed to have a spiritual side to us that requires nuturing for us to feel whole and to stop us from fearing our own inevitable death which in turn would make everything we do somewhat banal and without purpose.
For every question this might answer there are quite a few more that come up in my mind that are not...

Our knowledge, that we are all going to die, actually makes us anxious and stressed and our "God " brain part developed so that we could alleviate this stress.
Mmmm...
So spirituality ( not religion ) is actually something that should be nurtured, as well as meditative states so that we can feel connected to the wholeness of all rather than be fixated on our finite ego self. ( which would send us all batty ). I would aggree with that.
From a logical and intelligent perspective this makes great sense.
This hypothesis is not new and has been studied by many scientists, psychologists, neurologists etc.. who have looked at the brain and what parts "light up" when certain sensations, situations and illnesses and drugs effect parts of it.
Again, there are many things that still are not quite covered in this theory.
Also the book says that we dont actually die straight away when our heart stops  - it takes another 6 minutes for our brain cells to get the oxygen they need ...then we die. Thats why heart massage is so important as it keeps the oxygen moving around the body and gets it to the brain and hopefully someone is there with a defribulator to give us the shock we need.
So we can get technical about "going into the light"sensations and also the feelings of calm and euphoria or meeting God that many people feel before death and explain them as an automatic body response to imminent death.
We can break down every process into a normal function of our body/brain that has developed coping mechanisms over many thousands of years.
Its proven. Its been studied and documented.

We need to be spiritual ( most of us ) just for our own sanity.

But all of this discounts a God that is outside of us. As we have created a need for him so that we can function in this world and to make us more special than any other animal that is on this planet.
mmm..and where does this put stuff like "going into the light", "out of body experiences", "ghosts and spirits"...we all have to make up our own minds about that stuff.I guess I am still working on my own explanations and am out to read as much as I can to give me material to think about.
I do warn you though, just dont pick up any scientific texts....if you werent an atheist beforehand...you might just well consider it afterwards.