If a music director wants to have a Christmas show with religious songs, he or she has every right to do so without governmental interference. These types of decisions should be left up to the community, school district, and the school board. The federal government should be protecting these religious liberties instead of trying to banish them. Even many Christians have been deceived by the Separation of Church and State propaganda. That is partially correct.
Students can pray and read their bible as long as no faculty member initiates it.
But they did not reach that decision based on the Constitution. They take a warped view of that document and try to fit it in with their real agenda. Which is to remove the Christian influence from all areas of public life. Well, remember this much. Congress has jurisdiction over the Supreme Court.