MC I would like for you to point out to me a law or a supreme court decision that hold displays of nativity scenes on public property unconstitutional.
"Under current law, government entities (city halls, courts, public schools, etc) can generally acknowledge religious holidays so long as they do not create an impression of endorsement of religion by the government.
For instance, local towns can display a nativity scene so long as they include a fair amount of non-religious, or secular, symbols such as reindeer, candy canes, toy soldiers and so on, along with the nativity scene.
If the display does not include such non-religious symbols, it may be seen as an unconstitutional government endorsement of religion.
Just because a nativity scene or other religious display appears on government property does not necessarily mean that it is owned or is being displayed by the government, using tax dollars. Many local and some state governments have within their boundaries public areas whereby citizens are permitted to erect displays, including those of a religious nature, of their own choice. If you observe a religious display on government property, you may want to consider the following steps to investigate the situation:"
American Civil Liberties Union of Ohio :: Nativity Scenes & Holiday Displays