The belief in the supernatural is not based on universal natural observations but by personal convictions, which is why there's so much disagreement between the countless faiths that exist. As for why they all share similarities, that's likely because they are all created by humans, who tend to share very similar core values and have a limited range of experiences.

When someone asserts a belief contradictory to my senses and to basic logic, i will absolutely disregard it. My general nihilism isn't so much a belief, but how I've been shaped by my observations and experiences. It's not some belief or identity. Just seeing and reacting, simple as that.