Many belief systems arise out of fear; Fear of the unknown, suffering and uncertainty of life. The existence of such beliefs or the urge to create new, is what makes us function as living and breathing units of nature. So in retrospect supernatural or otherwise beliefs that give purpose, hope and certainty may be an evolutionary counter weight to the rational part of the brain.
The human brain, even at its finest, although may not be alone, is completely incapable of an objective understanding of the universe. Because it cannot directly interact with anything without creating mental constructs to act as conceptual buffers. Many conflicts are merely inconsistencies between these constructs and the external factors themselves. So whatever fears lurking in the back of your head are there because you are afraid of the inevitable conflict.
But the good news is before you were born, this subjective universe of yours didn't exist and without you it won't continue. So what you are really afraid of is the volatile nature of your mental constructs and the pain they produce midst of change.
And yet when you see the slightest hint of sickness or pain in your child, you'll probably kick your rational brain out the door and start praying to every god you can think of. So let's not be ashamed of our invisible tail and embrace the balance it brings to life.