"No academic skepticism, no secularist authors, no blatant materialism can so undermine the spiritual life of the country like the completely secularized training of the child under the authority of the state... Bible-based education is mandatory for Christian parents. If we think we can keep our children in a secular school system and escape the dumbed-down, amoral, and immoral results of secular humanism in schools, we are sorely mistaken" (Dave Black; emphasis added)
Read more here.
2 Corinthians 6:14 (NIV)
Do not be yoked together with unbelievers. For what do righteousness and wickedness have in common? Or what fellowship can light have with darkness?