Atheism is sometimes hard for people to grasp. It's a lot like people who choose not to have romantic relationships. Lots of people assume they can't maintain a successful a relationship or "just haven't found the right one yet." They assume relationships are the right way to be and that for anyone who doesn't have one there's something wrong. Sound familiar?
But more than that it's a choice like religion is, only it's a choice to have nothing in that area of their life. Atheism isn't a religion any more than a person without a relationship is in a relationship.