I don't know of any cases where a person was declared brain dead and then came back to report on such events. Not saying it can't happen, but I haven't heard of any documented cases. Only stories. Still, even if it did happen, all that tells us is that we still have a ways to go to understand what brain death really is. There may be (and probably are) processes going on in there that we haven't yet learned to measure. Perfectly normal, electrochemical processes.
There are a lot of motivations. A big one is the need for people to believe that they are special, and being created by a magical being who wants to give them some eternal reward or something fills that need. But I think the biggest motivation for belief is fear of death. Some people just need the comfort of believing they will carry on after death.And maybe on a need for something bigger or better than humans?
As I've said before, you can provide all the evidence against the existence of something and still not prove that it doesn't exist. And while the "absence of proof is not proof of absence", you could show that the absence of evidence for the existence of gods IS evidence of absence. Most people don't believe that unicorns exist, but you cannot prove they don't exist. It's the absence of any evidence to show that they DO exist that lets us claim that they are not real. And that can only be a tentative claim, though very strong, because we cannot prove that one will not pop up on the White House lawn tomorrow morning. Just don't hold your breath.As our old discussions show, there is no proof of God/Gods but absence of proof is not proof of absence and, no one could proof that there isn't or aren't gods either.
The same holds true for gods. No matter how many people believe that gods exist, the lack of any evidence to show that they exist is a big mark against them. The fact that there are so many different interpretations of gods is a very strong indicator that, at least, just one God does not exist. And the fact that even those who DO believe in this one God all have different opinions about his expectations of them is another large piece of evidence against Him.
So yeah, I cannot prove that anyone's god does not exist, or that any gods do not exist. But I'm not making the claim here! If I was to claim that gods cannot exist, then I could be expected to prove it. It is those who DO make the claim that gods, or a God, exist that need to provide the evidence. But all we get are suppositions and gobbledygook. And the charlatans continue raking in the money.