If it is a religious matter to teach—or imply—that the Bible provides a standard for moral order, is it not also a religious matter to teach—or imply—that it does not? If it is a religious position to say, 'Jesus is Lord of all, and by Him and through Him all things exist,' is it not also a religious position to say —in so many words, or lack thereof—Christ and the Bible are irrelevant to our discussion on biology, art and math?' Are not both statements religious statements?
To teach students that Christ and the Bible are irrelevant to biology, art and math can be done very effectively without telling them this directly. A teacher does not have to stand in front of a class and say 'the Bible has nothing to do with our discussion' to communicate the message that the Book is irrelevant.
If we think the current U.S. system of education is religiously neutral, we must think again. If state schools were indoctrinating children in Buddhism, Islam or Native American Animism, many Christian parents would hit the ceiling. Maybe. But when it comes to the indoctrination of children in John Dewey's so-called 'Common Faith,' which he referred to as a non-theistic faith, Christian parents are curiously passive.
For more from Christian Overman, look at his free e-book, The Lost Purpose for Learning.