The maverick philosopher, Bill Vallicella, discusses Is Heaven Real? A Neurosurgeon's Near Death Experiences, and offers some very good insights:
A second concern of mine is this. How does Dr Alexander know that his wonderful experiences didn't suddenly arise just as the cortex was coming back into action just before his eyes popped open? So even if his cortex was for a long time completely nonfunctional, the experience he remembers could have been simply a dream that arose while the cortex was coming back 'on line.'
My point is not the the doctor has not given us evidence that mental functioning occurs in the absence of brain activity; I believe he has. My point is that the evidence is not compelling.
Our predicament in this life is such that we cannot prove such things as that God exists, that life has meaning, that the will is free, that morality is not an illusion, and that we survive our bodily deaths. But we cannot prove the opposites either. It is reasonable to maintain each of these views. Many arguments and considerations can be adduced. Among the evidence is a wide range of religious, mystical and paranormsl experiences including near-death and out-of-body experiences. The cumulative case is impressive but not conclusive. It rationalizes, but does not establish. Philosophers. of course, are ever in quest of 'knock-down' arguments. This is because you are no philosopher if you don't crave certainty. Ohne Gewissheit kann ich eben nicht leben! Husserl once exclaimed. But so far no 'knock-down' arguments have been found.
In the final analysis, lacking proof one way or the other, you must decide what you will believe and how you will live.
I would add that the 'living' is more important than the 'believing.' It is far better to live in a manner to deserve immortality than to hold beliefs and give arguments about the matter.