How can you break into a conversation about if they are unsure if there is a God or not? How do you find out that they are an Atheist?
One effective method to ascertain someone's beliefs is to pose a question such as "Do you believe in God?"
If their immediate response is not "No!" ask this: "If you believe that there is no God, we will call this a zero (0), or if you are absolutely certain that there is a God, we will rate this a ten (10). How would you rate your belief on a scale of 0 to 10?"