If the children are forbidden to see the the movie all the children are being taught that Christmas is somehow shameful and must hidden out of public view ( like a bathroom activity).
It the children do see the movie, those who do go will inevitably subject the atheist children to a movie review of how great it was.
Neither is neutral in content or consequences and this is true for **thousands** of curriculum and school policy decisions in which a binary action must be taken.
When government supports school it always **establishes** non-neutral religious worldview. At the moment the atheists are winning.
Silence in the face of evil is itself evil: God will not hold us guiltless. Not to speak is to speak. Not to act is to act. DIETRICH BONHOEFFER