Digest of terms
the certainty of death is fundamental not only to life but to the notion of morality in life. Like at least some other animals, human beings are aware of death. They know that one day they will stop breathing and that bodies turn to dust. A mythological search for an elixir to prolong life emerges as invariably self-defeating, and the current medical initiatives designed to prolong life generate as many fears as they do hopes.
To a minority, death is seen as demonstration of the ultimate futility of life, even giving total licence to do anything - or at least anything that you can 'get away with'. For rather more, it is today's invitation to 'eat, drink and be merry', because tomorrow will be too late. To yet others, death is a horizon within which to plot the living of the best life possible, with varying degrees of inclusiveness of those recognised as warranting care (nationalism, Humanist ethics, Existentialist ethics).
Religious worldviews are often presumed to provide ultimate rewards and punishments for the way lives are lived. However they are conceptualised, this is a function which heaven and hell are believed to perform. Analogously the law of karma is an impersonal mechanism ensuring that good and bad deeds generate good and bad consequences (not quite the same as rewards and punishments, which imply a personal mechanism), if not in this life then in a future reincarnation or rebirth. Remove any belief in the prospect of post-mortem survival and, many would claim, all serious constraint on human behaviour disappears.
Arguably, though, in practice even religious worldviews with strong teachings regarding an afterlife have a greater preoccupation with life in this world than with any beyond to it, drawing attention to such moral priorities as care for others (altruism, Golden Rule), individual responsibility, personal freedom, the matter of truth, and pursuit of justice. They raise questions about the relative claims of family or friends, of employer or nation, of age, gender or race, and of humans in relation to other living creatures (animals