Why do some people claim that belief or lack thereof is a "choice"?

If a person has a brain and does use it then questioning what they think they believe and arriving at a different conclusion because logic guides them there, then yes they are making a choice. It was this process which led me from being an atheist to being a Christian. If people simply go with the flow and never use their brain and never question, then they, like you, can go through life in peaceful oblivion of what is truth.