Here's an astonshing bit of major discovery, and one might say of assertion of certainty: Investigators have found that 'near death' experiences are 'all in the mind.' The evidence shows, the investigators say, that normal brain activities--essentially, the imagination--can construct imagery that people who recover from what they sometimes claim are near-death states report that they have seen.
The investigators seem very sure of themselves, but how can they be? One can do all the brain testing one wants, but that simply cannot answer the question.
The real question is whether there even is a question here. The evidence for claims of life after death has always been largely imaginary. From claims that a Pope performed miracles, to sacred images performing miracles, to claims of answered prayers, there really is no serious evidence--from a scientific point of view. From that viewpoint, such claims are beliefs rather than evidence.
One can put it another way: science is about things that are part of the material world as we know it. Evolution may have taken place in the past, where we can't observe it directly, but we do have wholly consistent material evidence supporting ideas about the past and with predictive power about what we will find in future evidence in terms of general pattern and so on. We can't see molecules in the usual sense, but instrumentation allows us to study them. Though our usual instrumentation cannot detect it directly, even dark matter can be studied indirectly, through normal materially-derived means. That is what 'counts' for science.
We can't see souls, angels, or God's will. In a sense, if we could they would not be souls or God, as defined in the western conception of a world of eternal immaterial spirits. The afterlife is basically by definition beyond the reach (or purview?) of science. But if claims were true that the spiritual universe affects our real one, they necessarily involve material intermediary. A miraculous event has to occur in our physical world. So, obviously, near-death visions have to occur in the brain, and could in principle be studied in terms of brain activity observed when the subject reports talking with Jesus. From a scientific point of view, one is likely to deny the literal truth of such reports, but observing brain activity is in now way whatever relevant to that truth. It is compatible with the brain, somehow that we don't understand, having the ability to receive and respond to 'signals' of some sort from the immaterial world. It's just that we have no evidence to support such a speculation that bears scientific scrutiny.
Scientists may be--indeed may be overwhelmingly likely to be--totally right to think that such reports are due to internally structured imagination rather than externally or immaterially caused. But to claim that they know this from material evidence is a presumptive claim because the kind of evidence cited is simply irrelevant to the inference being drawn.