When my now 18 year old daughter was in 2nd grade, her class was told by her teacher to bring in a book to use for silent reading. She brought her childs bible. The teacher confiscated it and told her to take it home. We did not fight it but explained to our daughter that the teacher was wrong. From that day forward, my daughter made it a point to find out where her teachers stood on God. She also became some what of a rebel herself.
Please do whatever it takes to get your children out of public schools! The older they get, the more important it becomes...