In this post, James Robertson discusses Richard Dawkins's drive against religion, which drive I generally agree with, but I think it misses the point in some ways.

It is not necessary to teach people not to believe in God, but it is necessary to convince them that reason comes first. Faith is not a problem if the believer is willing to adapt when confronted with facts that conflict with his faith. But faith is a problem if one isn't so flexible - when one puts faith ahead of reason in one's value system. This leads to fanaticism, terrorism, abortion clinic bombing, dressing up women in burqas, female circumcision, and so on.

It is very necessary that the school system develops the students' rational analysis skills, to give youngsters trust in their reasoning abilities. Beyond that, teaching them not to believe in unicorns or witches is pointless, because what else is more interesting than what you aren't supposed to do, think, or believe.