There are more things in Heaven and Earth, Horatio, than are dreamt of in your philosophy
- Hamlet
As an atheist, my greatest difficulty is with bereavement rather than my own mortality. I know that matter/energy is conserved and that the material form of a human being is recycled rather than lost. However, for me, this is no solace. The unique pattern of mind of the person who has died is so much more significant than the reusable atoms of the physical substrate that accommodated the pattern. To contemplate the abrupt disappearance of all that beautiful and much loved complexity is hard.
At the same time, I cannot bring myself to believe in God and heaven in order to reassure myself that the dead continue in some way. Reality is as it is, regardless of the more bearable outcomes we might conceive of.
For me, the only loophole that offers a small glimmer of hope is that we still don't fully understand the nature of consciousness.
The orthodox scientific position is that consciousness is an emergent property of a sufficiently complex living system and cannot exist independently of that system.
Another possibility, albeit one less favoured by mainstream scientists, is that consciousness is merely hosted by the brain, so that it can interact with the physical world through the brain in life but may separate from the body at the time of death and exist outside of it. This might sound like a convenient fairy story but strangely enough there have been many documented cases of people who have clinically died - their heart has stopped and no brain activity has been measurable - yet subsequently they have been resuscitated and have recalled 'experiences' that support the idea of mind-body separation. No more than the false recollections of brains in extremis? I do not know. The evidence uncovered in the scientific work of Pim van Lommel, Sam Parnia and others in the area of Near Death Experiences is intriguing but not definitive.
Could there be a continuity of awareness outside the body after death that is entirely natural, yet not within current scientific understanding?
An afterlife determined by an anthropomorphised God who rewards the chosen few that adopted the 'correct' set of beliefs in life and punishes the rest seems unlikely to me, though many thoughtful people have come to the opposite conclusion. Oblivion really does seem the most likely scenario, yet I cannot but hold onto the hope that neither the conventional theist nor conventional atheist picture is true as neither appeal to me - not that the universe cares about that!