[we, as a society, have a very narrow view of the world.
we make an effort to filter and categorise all the things we do not understand into systems that can be easily explained away, allowing us to feel secure in our knowlege that everything is okay around us.  Sleep, eat, work, repeat, carry on the sense of a secure and mundane life. Society is stable because we know our place and stick to it, without fear of the unknown making our lives difficult. Evil things that hide under the beds of children are nothing but imaginations, lost to the fog of distant childhood memories. We don't need to fear things that don't exist.
The fey and incomprehensible things that live within the cracks in a reality held stable by normality.
Creeping, skirting around the edges, looking for ways to bring their discord into our order. Wishes and nightmares given the breath of life, old gods long since lost, powerful and infinite darkness held back by floodgates.
There are people who spend their lives, and indeed their deaths, protecting us from the dark that we can't explain away, that must be beaten back with gunmetal and flame. They keep an organised secret, make sure what lurks can never break into a commune ruled by logic. The supernatural doesn't exist - they make sure of it.
Our governtments have many branches that 'don't exist' to the general public, secret sodiers to fight secret monsters - people chosen specifically for their skill and discrection.]