This is more relevant than most people realise. There is seemingly an increase in religion the older you get. As you said, fear of death and the comfort of something still to come.
When I was a kid I could not understand how that line was meant to be peaceful. Even listening to the rest of the song, it was still unsettling. I was raised Catholic so the song just starts with like “imagine the worst case scenario”.
As an atheist now, it’s more hopeful to me. Like imagine what the world could be like if we weren’t just biding time until we were dead. If we all just knew this was the one chance one opportunity mom’s spaghetti.
I mean.. the first thesis statement in capitalism is "there is a scarcity of resources" and that dominates our lives. Yet, not when we think of life itself.