Sometimes people have near-death experiences where they “die” for a while before being resuscitation. They are in some sort of accident or incident and are pronounced clinically dead, but come back after a few minutes.
Some of these people report seeing white lights, tunnels, gardens, dead loved ones, etc. while others report nothing. The ones who see something often end up becoming more spiritual and hopeful after their experience while the ones who saw nothing often end up becoming depressed and pessimistic, even if they had previously been spiritual.
The problem is that the people who see nothing decide that because they saw nothing when they “died”, it means that there is no after-life or Heaven or reunion with lost loved ones. This is absolutely specious reasoning.
These people are missing the point that they did not die. Why in the world would they be greeted with the post-life welcome basket if they are not dying and going to be resuscitated? Does it not occur to them that God would be smart enough to know if they are actually staying dead or not or do they think that they were supposed to die, but the doctors defeated fate/God and snatched them back?
Of course this raises the question of why some people do see things when they have a near-death experience. This is likely caused by differences in the nature of the near-death experience. Some people who are pronounced clinically dead have no brain activity while others do. The people who see things are probably not actually seeing post-life imagery, but rather hallucinations caused by a mix of their spiritual beliefs and their brain suffering anoxia.
The fact is that near-death experiences prove nothing about the existence or lack thereof of an after-life. Whether or not there is an after-life (at this point) is only knowable for sure by those who actually die, and stay dead, not by anyone who comes back, which of course, means that the living continue to have no definitive way of knowing either way.