Not exactly. Schools are not military units, and school personnel are not some representatives of the greater nation. They are members of a community who should reflect the ideas of the majority of the parents and children they serve. That would be the 85% of the public who are Christians or are greatly in tune with Christian values.
The other 15% can either tolerate the majority or seek private education. There is nothing in the idea of American values which implies the 85% should turn their backs on their religious beliefs and their social system in order to accommodated the wishes of every freak and pagan who comes along.
Schools should be an extension of the majority of children's home. Not some foreign "salad bowl" with nothing to ground them. Without values and the reason those values exist, what is the point?
As for the other 15%, learning and following the Ten Commandments never harmed anyone.
So, considering that only 22% of Americans support a ban on abortion, you have no problem with health classes in highschools being used to promote abortion as a means for dealing with unwanted pregnancies? After all, majority rules, right?