Not sure about that. Been an atheist since I started thinking for myself outside of the family line on such matters. I don't have a clue about a purpose & am totally accepting of that. Essence of my being? Not something I think about. I'm very aware I operate within an evolved system for better or worse unlike our earliest hunter gatherer ancestors & go along with it willingly, taking daft pleasure in things such as retro MTB's. Old age - I worry about physical or mental decline but not death. While death may be inconvenient my atoms will just return to the the random distribution they were in before I was conceived. No heaven - no hell. I'm cool with that.All human beings are drenched in insecurity about the very essence of their being, and it can be masked but it's still there. None of us have a clue. We make it up as we go along.