The "cafeteria" prayer is like a few friends whispering to themselves in the corner of a room. A checkers group could do the same thing discreetly. The Nativity Scene is a shrine to the Nativity of Jesus Christ, placed in a public corridor. Although it doesn't offend me, it tells everybody in the school that the corridor is a Christian place. You either don't know anything about  your own religion or you hide behind fake logic and diversion.