Agnostic here brought up with Buddhist grandparents. I like the idea of reincarnation - (I don't deny not truly believe it) you need a "soul" to leave you physical body and to repeat in an endless cycle. Nirvana is when you break free of this cycle and gain enlightenment.
The idea that a part of us may live on has helped cope with mourning a lost one. But that's really it - in the face of mortality, sometimes you find mechanisms to cope. Don't think I answered your question...