Atheism is not a dirty word but rather a very sensible view on life. When it comes to children the churches tend to filter into their thinking with the idea of a god who threatens hell. Atheism on the other hand garner toward healthy and moral living with consideration for equality and secularism.
I consider using a threat like the idea of hell as a psychological attack and not a very healthy way to sell an idea, particularly since hell is an idea and does not exist.
Children should be allowed to grow up with secular guidance and should they desire the controlling atmosphere of religion then let them make that decision as informed adults.
Children are innocent, and they should not be taken advantage of by systems of belief that separate them from rational non-believing thinkers of secularism.