I've always been fascinated with astronomy and cosmology. And to quote one of the scientists from How te Universe Works (or Through the Wormhole): "We are all stardust," born of supernovae that created the spark of life. So ashes to ashes, stardust to stardust ...
It was Sagan who famously said “The nitrogen in our DNA, the calcium in our teeth, the iron in our blood, the carbon in our apple pies were made in the interiors of collapsing stars. We are made of starstuff.”
And this is, I guess, why I don't personally understand religion. And I am speaking in very broad terms here -- I know what follows does not apply to all religions or all believers: I can understand how religion is likely to have evolved, but I don't understand the drive to believe. Isn't the natural world enough? Isn't it beautiful, bizarre, curious, and profound enough on its own? Why must we cling to a supernatural, when there is so much wonder yet to be understood. To me, our habit of "projecting our own nature onto nature," to quote Sagan once more, seems trivializing, and it is the height of arrogance to imagine that it was all created just for us.
Fear of what comes after. The fear of death can be a powerful motivator to believe that there is something beyond this life, that no, you don't have to end. That is the basis for many religions. The trappings were added later.
I would like to add that myths were conceived by ancient civilizations to make sense of the world and phenomena around them - life, death, birth, sunrise, sunset, light and darkness, etc. If early humans had the knowledge and understanding of everything that we do now, I doubt there would've been any use for religions at all. Yet the belief in a higher power is so ancient and is such a strong driving force that religion has become a way of life for many people all over the world. And I don't think it's going to disappear anytime soon, unless an asteroid suddenly happens to wipe humans off the face of the earth.