I think both concepts, "life stream" and "spirit", spawn from most people's inability to psychologically accept their own mortality. There is nothing in the way of credible evidence to suggest that our consciousness lives on in any manner.
Do you remember the time before you were conceived? (Proclaimed past-life regressions aside), that's all death should really be. People talk about ghosts, spirits, the "after-life", reincarnation, etc., and the sum-total evidence to support any of it seems to be zero.
We die, our consciousness ceases, the physical matter which makes up our body is recycled through the planet and eventually through the universe. Why isn't that enough for people?
My suggestion is that it's counter-intuitive for people because everything they experience of the universe is experienced through their consciousness. Attempting to contemplate experience without consciousness is impossible. It's the same reason people have so much trouble grasping physics other than on the Newtonian scale. We live our whole lives interacting with Newtonian-scale physics so anything else seems counter-intuitive and wrong, even when the objective evidence shows that it's right.
We know nothing but consciousness. Those moments when we are unconscious are so few and far between and so devoid of experience that we're unable to count them as any kind of experience because a lack of consciousness is the complete lack of experience. We don't remember the time before we were conceived because we lacked consciousness through which to experience that time. Once we die, we'll have that same lack of consciousness. On a mental level, we simply cease to be.
That might not be fulfilling, comforting or desirable to most people, but it's what all of the credible evidence suggests. I'm not prone to believing things just because they appeal to my personal and/or emotional desires. If I'm alone and I don't like being alone... I'm still alone. If I'm at work and wish I were home, I'm still at work. If I'm going to die and cease to be from any kind of conscious level, nothing I choose to believe to the contrary will do anything to change that. We can accept reality or deny reality.
From the best we've ever been able to determine, acceptance of reality leads to expanded capabilities to have some level of control over that reality. Denial of reality leads to superstitions, irrational fears, persecution, human-sacrifices, cruelty, pain and suffering. I'd rather promote reality than emotionalistic, desire-driven fantasy.
I realize I'm in the minority so here is the challenge: Present credible evidence to show that I'm wrong.
;)
