I don't think anyone has a "right to not be offended." That flies in the face of exactly what it means to live in a free society. You can be offended, and you should be offended when you come face to face with opinions and ideas vastly different from your own, that's part of freedom. And this has nothing to do with that (or at least shouldn't).
Talk of Christianity isn't banned from school either. It's discussed in a historical context all the time. We read early Christian literature (Dante's Inferno, Paradise Lost, etc). Evangelizing is banned from school; just as trying to convert people to the homosexual agenda is, and should be, banned from school.
This case is pretty ridiculous.
EDIT: As for the pledge of allegiance, it should also be banned from all schools until the "Under God" b.s. added in the 1950s is taken out. Government and Religion need to remain absolutely separate at all times. This is a nation under popular sovereignty, not a deity.