As far as I can tell, the feeling or hope that many of us have for intelligence after death is based almost entirely on communication with beings that are already dead, or at least not alive and also invisible. I have had such personal experience.
I sponsored all the Cambodian refugees in my town and in addition, many of them had such experience. One was even able to consult with her dead ancesters and siblings when she would have rather mundane problems like buying a new car.
All the revelation in the bible and other scriptural sources are essentially of that nature- words from an invisible source. The accuracy of biblical prophecy is one way to establish that the information communicated came from a source outside of our own subconscious. For example, circling the walls of Jericho 7 times is at least prophecy and at most implies the existence of God.
In my case, I could determine that the information I received in several cases was not known to me or my channel. So there was an invisible source of accurate information. However, not strong evidence for any definition of a god.
So evidence, although subjective and not repeatable, exists for invisible intelligence and part of the evidence comes from once alive and now dead beings. Hence the belief that there is life and consciousness and intelligence after death has a basis in common experience, not just in religion.
In Asia the experience is so common that there is no question about life after death. However, the concurrent belief in reincarnation implies the existence of a second death. In order to be born again, you must lose all your memory of a previous life. On the other hand if you are sufficiently developed spiritually, perhaps you may elect to stay in heaven. But I suspect that there may be cycles to higher levels of heaven that also require a loss of consciousness and rebirth to attain. So sooner or later we must all accept the end of our consciousness, but perhaps not our identity.