I believe it an oversimplification to say that doubt or belief are merely choices. Our mind's capacity to believe is a fascinating phenomena. I'm not a neurologist nor psychologist, but I suspect that there are multiple factors at play, even subconscious protocols that employ variables of upbringing, environment, experience, education, mental health, emotion, personality, and trauma to name just a few. All these quietly influence our state of perception, belief or disbelief, outside of our conscious and deliberate thought.