when Neelix dies for 16 hours and is resurrected feels a loss that he didn't end up under that great tree in his "afterlife". That episode heavily implies there is no soul
I interpret that episode like this: The very fact that Neelix was able to be brought back is proof that he was never dead in the first place. So the only way he could have moved on to his afterlife was if he was truly dead. They brought him back, so therefore, he was never REALLY dead.