According to many parts of the bible, AND other writings not in the canon........Jesus himself said NO FLESH can INHERIT the kingdom. You MUST be BORN AGAIN. Some are born of flesh, and some are born as spirit. Then Apostle Paul couldn't wait for a release from his 'fleshly' body, and was running the race for the 'greater calling' to share in 'divine nature'. Then there is the scripture on man being appointed to die, ONCE, for all time, THEN a resurrection/judgement. So to me, reading those scriptures, means that being born again means a real actual death, then being reborn as a spirit. (or for those of the annointed/ elect)
In Book of Enoch I think, God says how humans were never meant to live forever, flesh is appointed to die, and that is why he gave them wives. However angels, those of spirit, CAN"T DIE. And how when they mated with human girls, the 1/2 spirit, 1/2 flesh monsters. When they died, their flesh was gone, but their spirit is stuck on earth and THEY are the demons. The rebellious angels who did that, were cast in the abyss and are still imprisoned there.
Makes sense, in the way of being in harmony with many parts of the bible. It does not make sense on living forever on the earth, etc.
This may clear a few things up, but I already know the billion questions it will raise, and pretty much this line of thinking adds a whole new dimension of possibilities, but also explains how originally going to heaven, etc, began to be understood.