That is an apparent good for you. But your children will live in a country where many will be indoctrinated. How free will they be, if the majority of its citizins are pawns?
Can your fears by addressed in another way: could not the law allow a private school category where it is required that the school and parents enter into a contract to forbid voucher aid to the parents. In return, the school is categorically exempt from any government interference - (of course, at this stage this presumed government interference of the private school is a concern but not a foregone reality.)
could not the law allow a private school category where it is required that the school and parents enter into a contract to forbid voucher aid to the parents. In return, the school is categorically exempt from any government interference You're suggesting that the government would allow itself to be bound by a non-interference contract? Sorry, we know better. You don't get within a stone's throw of government money without government control; ask Hillsdale College.
I can't control what other parents do, or how their children turn out. It appears that a majority will put up with anything as long as they have somewhere to leave their kids all day. Without a major change of heart on the part of millions, we'll just have a growing number of bread-and-circuses zombies.
How free will any of us be? As free as owning land and guns can make us. Everyone has to die sometime, if it comes to that.