I do not expect to be resurrected, but I will live on in the memories and love of those who survive me. Samuel Scheffler, the philosopher, proposes thought-experiments to show how this affects everyone:
How would it affect your life if you knew that humanity would end thirty days after you died?
Would it be different if everyone was aware of this?
Then, from The Children of Men by PD James, what if no-one ever gave birth again? Humanity might continue another ninety years, but our ending would be inevitable.
Does it matter when humanity will end? In Annie Hall, a child despairs- and stops doing his homework- because the heat-death of the Universe in however many billion years means that everything is pointless. When the Sun becomes a red giant it will envelop Earth, and before then its increased heat will cause global warming. But then global warming may do for us by the end of the century.
For Scheffler, many activities would no longer have meaning: why research on cures for cancer, or any long term project? Why should he write his paper? I would transfer my loyalty to the biosphere: humanity would die, but Earthly life would continue. If all life on Earth would die, right now there are human beings with whom I might relate: my acts would have meaning now even if never after. An instantaneous cube exists for an instant, and most things we do have little meaning even a day later.
Knowing that the lives of others after our death, whether our descendants or not, give meaning to our own lives changes how we consider problems now. Rather than imagining that we should make sacrifices to mitigate climate change for the good of those who come after, we would realise that we make those changes for our own good, to give our own lives meaning.
I wonder if this applies most to altruists. Each person’s comfort matters to that person, and there are some for whom nothing else matters.