the idea of life after death was introduced to me solely through Christianity. it cannot be proven or refuted since no one really comes back, and if they do we don't know whether or not to trust their stories.
if you look at life without any ideas or bias, nothing really points to a life after death other than the written word. it just depends if that written word harmonizes with your idea of life.
do i believe in a life after death? i believe that ghosts/spirits are real, so yeah.
but one of the heaviest aspects is the idea that time will never end. that there is no end, your death doesn't mean you stop, just the beginning of the infinite, which is a lot to think about. if a religion that thinks this turns out to be true, then there is no end, just continuation. that's intimidating, but I've read conversion stories where people said they felt like the dimension of time was destroyed and had no use. if heaven transcends time perhaps infinite isn't an issue.