Atheism is a not based on belief. It is a position they take. They take a position which is convenient to take and which makes them comfortable. By doing this they do not have to look for evidence, they do not have do any kind of research, they do not have to bugged by any rules and they are free. All they need to do is to reject ideas and mock at everyone else who do not agree with them.
Now-a-days they define atheist as a person with no belief of any kind. By this definition we could conclude that they do not believe what they preach. Now we still have to preach. We need to do so, to warn them that they are on their way to the eternal fire.
Since they do not want to believe, it makes no sense to expect them to believe in a God. It is a question of will.