Which is why the public school system is flawed. Used to be the schools were held in churches. The books had Bible passages to aid in reading and writing comprehension, printed by the government. No one complained as teaching was free and excellent. If you did not like a church, usually one you did was near, though many states back then did trend toward varioud denomonations.
Public schools now have the agenda of the government running them and see what it has produced. We need to go to a voucher type system where you choose which school you want your child in. If you are a good school, you will gain more students, competition is good. Don't want your child learning the Bible, put him in one that does not teach it.