It's just a belief

In the beginning humans were life that struggled to survive. The strongest and most prolific (and luckiest to be in the most hospitable place at the right time) survived. Each individual was out for themselves. There was no family there was no group there was no future. There was only now. They struggled to survive then they multiplied.
     Then what is now known as human evolved into a being that understood the time line of family, my progeny, the loins from which I was begat, the bigger, stronger, smarter being that protects and feeds me and at this point offspring were no longer food. Offspring became your destiny. Offspring became what you left behind.
     As families banded together to prosper order had to be applied to the social unit. All procreation was not OK. And taboos and rules had to be applied to maintain order. ‘Thou shalt not’ came into being and a new goal was offered up to replace the procreation goal. ‘If you follow the rules you will live on after death.’ And so it has been to this day.’
     At some point the idea of life after death will become unnecessary. Death will be overcome by science and fear of it will free us from the fear of ‘thou shalt not’ and belief in life after death will go away along with it those who have controlled those that believed.