It's naive to believe that as your brain is being deprived of oxygen that it isn't capable of playing tricks on you.
Yet again, I hardly know where to begin there is so much wrong in this statement. No one says that near death experiences are all induced by chemicals or drugs. Oxygen deprivation works just fine. As does the delirium from a high fever. Or any number of other possibilities.
How is a blind person describing what they "saw" unless they've seen something before?
So now out-of-body experiences prove the existence of god? Even if you could show there was a soul, and it was capable of an out-of-body experience (which I won't grant), you could not then use that to prove the existence of heaven or god. Lots of cultures have beliefs about souls that are not connected to a belief in god (i.e. they are incidental to god belief).
If the guy was "dead" in his coffin for three days, and then "came back to life", it's probable that he wasn't really dead at all. If his body hadn't started decomposing, that would be a pretty good bet. And without sophisticated medical equipment, it's not as difficult as one would think of confusing a deep coma or other state with death.
And yes, I've heard of quite a few people describing things that were hallucinations or dreams and confusing them with reality. Our theist has obviously been blocking it out.
You don't have to be silly to be deluded.