For most of my life I had a false understanding of the Christian belief in everlasting life: I thought it was about living an eternal life as a spirit. I assumed that the stuff about resurrection in a new body was a primitive superstition, which no sophisticated Christian believed.
But my understanding is very different now. I now assume that the intuition of every childhood, all historical cultures and most of the modern world is correct: that the soul survives death. The question is what happens next, or what state is that surviving soul.
The human soul is meant to be united with the body, therefore after death of the body there is a degree of maiming.
So death of the body is indeed 'a bad thing', as we naturally suppose, and survival in a spiritual realm does not make up for this.
(Indeed, the 'natural' post-death survival of the soul may itself be most of what people describe as hell - I am impressed by the ancient Jewish idea of Sheol as a realm of witless gibbering ghosts, human souls minus the body may be like that - each ghostly spirit in its own horrible unending isolation.)
Immortality, popularly conceptualized, is continued life - life as it is now but continued indefinitely.
But this has nothing to do with Christianity, rather it was what Christianity was intended to cure; and indeed continued spirit life solves none of the deep problems of life; neither does reincarnation (leaving-aside the question of whether reincarnation is true in this world).
To imagine that immortality (continued existence) or a system of reincarnations (recycling of the soul through various bodies) solves anything fundamental seems to be simply a misunderstanding - a non sequitur.
So what is the Christian belief?
Christian salvation involves the soul surviving death, then the saved soul being resurrected in a perfected body to dwell in heaven.
The process of resurrection is not a restoration of the state of humans on earth; we as we are are not reborn again to a continued existence; but there is instead a re-making of an unique human into an unique Son of God - retaining each individual human nature (staying essentially the same person) but enhancing - indeed transforming - this nature.
It's simple enough isn't it? And I had heard this often enough, but somehow it didn't get through to me...