seperation of Church and State
not to mention that if you have multiple religions in a room and you offend one with the teaching you're screwed.
EDIT- I have to agree with whoever said we should have a religious history class, we have one at my school, and some people come out of it with a changed view on life, they aren't as cruel to others and it makes getting along better for the Muslim girls who wear the hijab and the men who wear Yahmakas at my school