66 In any case, the more burdensome the material sacrifices demanded of the individual and the family by the State, the more must the rights of conscience be to it sacred and inviolable. Goods, blood it can demand; but the soul redeemed by God, never. The charge laid by God on parents to provide for the material and spiritual good of their offspring and to procure for them a suitable training saturated with the true spirit of religion, cannot be wrested from them without grave violation of their rights.
Source: Summi Pontificatus (Vatican.va)