Suave

Everything is a belief; even the choice not to believe in something is still a belief. It is absolutely impossible to be a sentient being without having some sort of beliefs. The choice not to believe in something is not an absence of belief, it is just a "negative" belief toward that concept.

Now, for a bit of a tangent.

They, like everything else, are a very limited choice. Basing this scientifically, you are born with genetic dispositions to certain cognitive attributes. Then, you are raised and socialised in a way that further affects the way in which you are most likely to perceive things. There are variations within the framework provided, but it essentially dictates the boundaries within which your beliefs will fall.

I don't personally subscribe completely to the scientific view of it, but it's the one that I suppose could be argued to be the most credible.