Atheists are the most sensitive of creatures. Some feel physically ill at the sight of a cross, and would prevent the cross-shaped wreckage found in the 9/11 ruin from being placed in the 9/11 museum. (Steven Colbert noted that apparently the cross will spoil their good times at the 9/11 memorial.) It sounds as if they need psychiatric help but they've gone to lawyers instead.
Atheists and their legal opponents are overlooking one glaringly obvious point. Atheism can obviously be represented by nothing. Therefore, anyplace you look and see nothing — perhaps a cloudless sky? — can be ascribed to nothingness. The presence of air molecules covering up the vacuum of space is a point for lawyers to quibble about. But any place where there is no man-made religious symbol can be consecrated to atheists. That covers a lot.
Once we accept that lack of crosses and so on says "atheism" all that remains is for Christians, and whoever else wants to jump in, to start suing atheists for forcing emptiness on the rest of us. No religious symbols on the lawn of city hall? It's the atheists pushing their lack of beliefs on other citizens.
Thus no space will be free of legal bullying. The only way out is to sell every patch of ground, building space, or sky view to commercial interests.