don't mind them teaching evolution, but they shouldn't slander,joke,or mock a religion when its most definitely has nothing to do with that their teaching. "if its not in the text book" it should not be taught".
I doubt that there is anyone here who would disagree with you on this. Religion has no place in the science classroom: either in favor of it or mocking it.
Separately, mocking someone from a position of power (on any topic) is unfair and a practice that a principal should strongly reprimand.
So this issue is not really on topic here at all. It has nothing (as best as I can tell) to do with the teaching of evolution.
If you wish to tell us more detail about this incident (such as what was said in mockery). You could open a new thread in the Proposed New Topics area. Thanks, it should be interesting to everyone.