Checkmite
Skepticifimisticalationist
I am sure the court might elucidate that.
Is saying "someone is of the devil" provcative speech (which is not allowed in schools but is in society) or is it diecrininatory language which is allowed except for where sanctioned?
And what is the intent and cultural baggae of 'of the devil'. That will be key as well.
Now it also just depends on the merits of the case as well.
It seems to me that for something to be "discriminatory", the rights of the person being discriminated against must be postively affected in some way. A shirt that says "Islam is of the devil" is not denying Muslim students a drink of water, access to restroom facilities, books, or the like, that non-Muslim students retain access to. In fact it doesn't really say anything at all about treating Muslims differently or denying Muslims their civil rights (or any other kind of right, save perhaps the "right" to get into the Christian version of heaven, which isn't a legally-protected right).
Further, if the fact that Islam, as a non-Christian religion, is of Satan actually is indeed a tenet of biblical literalist Christianity (which I believe it is), I don't think the shirt can even be called provocative or inflammatory speech - at least not in the sense that a person can be compelled by a court not to wear it, because freedom of religion comes with the right to describe and express religious beliefs, even those others find repugnant (e.g. Westboro), so long as those beliefs don't materially affect the rights of others. A Muslim student might be made to feel bad about himself or his religion when he sees someone wearing such a shirt; but the Constitution overrules hurt feelings so far as I know.