Belief in heaven is a human necessity; however its existence cannot be proven.
We do not have empirical data that could supply us with prima facie evidence to render it as there. Its existence cannot merely be proved by mere deductive reasoning.
The reality of heaven as fact is also a necessary human impossibility, because it helps us look beyond the complexities of the present, but rather look forward to what is beyond. Factuality is in the realm of science, and for Will Durant science is 'the captured territory' in the battle for knowledge while 'philosophy is the frontlines in the epic war' for wisdom.
Heaven as reality belongs to the realm of metaphysics which dares to explain the fundamental nature of being and the world, thus it cannot be seen by the naked eye that observes what is already there but rather it is seen through the eyes of faith, which is yet to be opened.
Belief in heaven is necessary because it addresses a fundamental human need.
It provides for the persons' need for belongingness, it helps people like you and me find our place in the grand scheme of things. It helps us make sense of things because it binds us to a transcendent purpose, to a grand cosmic narrative that is beyond ourselves.
Thus it helps not only live but it goes further by making this life that we have worth living. It teaches us that there is more to life than just living; it makes us not only live for the moment but to live a life that goes in trajectory towards a climax that would bind us to the ultimate end where all things and stories would finally find fulfilment --heaven.