"We are — as far as we know — the only part of the universe that’s self-conscious.
We could even be the universe’s form of consciousness.
We might have come along so that the universe could look at itself…
It’s such a lucky accident, having been born, that we’re almost obliged to pay attention.”
Consciousness is the greatest mystery of science.
The brain is involved in it in some way, but we aren't sure how. It could be that the brain generates consciousness the same way a generator generates electricity, if you hold to that paradigm, then of course you can't believe that there's a life after death.
When the generator is broken the consciousness is gone.
But it's also equally possible that the relationship between consciousness and the brain is more like the relationship of a TV signal to a TV set, in the case when the TV set is broken, the TV signal continues. And this is the paradigm of all spiritual traditions that we are all immortal souls temporary incarnated in these physical forms to learn and to grow and to develop.