> So if my religious teachings believe that abortion is a
> sin, can I use this to prevent the school from taking my
> daughter for an abortion without my permission?
Nope, but you can use it to not have an abortion yourself.
> Is it because my sin is a Christian sin, and thus not as
> important as a Muslim sin?
Nope, it's because neither of the examples you gave is causing YOU to violate your religious principles.
Oh really. Spoken like a true liberal lawyer.