Understanding what a human is, and how a human works is the most fundamental question.
The proper study of the above is philosophy. Not science, and not religion. Science and religion are storages of knowledge to be interrogated and to be practiced.
When science and religion are interrogated, it emerges that theism and atheism are not fudamentally different because the metaphysics of humanity solely relies on universal laws.
For the universal laws, there are universal entities, like light. These entities are both subjective, and objective.
The interation of things within these laws is life, and consequently, life can only have one meaning: the sustainance and subsistence of these universal laws.
These laws are eternal, and ipso facto, good. To be aware of them and to work within them is to be righteous. To ignore them is to be unrighteous.
Heaven is both a place and a living in awareness, use and conformity to these laws. Hell is the converse.
These laws can be called many names, according to culture and context, but they remain the same.
Finally, all truth must be psycho-physical.