Of course I didn't will myself to believe or not believe anything. My lack of belief in any gods stems from a lack of evidence for any gods. Because I'm a rational person who knows how to know things and who knows when facts are not facts, but merely things people decide to believe for no apparent reason.

I'm gay, because that's how I was born. It's something about me inherent to my genetics and other biological factors. I could not, no matter how hard I wished it, decide not to be gay, meaning I could not decide not to be sexually attracted to other men. That's just who I am.

All religious people merely decide that they believe certain things about gods or other supernatural phenomena. They could decide, and they often do decide, to believe something else — sometimes so completely different that it's incompatible with their former decision to believe things.

That's not an inherent human identity, it's a decision.