I used to go to a christian school like that. I ended getting expelled at the end of 8th grade because they had random house visits, and i had a nirvana poster on my wall. I was expelled because I listened to "rock and the like". Those places are strict. But, I say the school was in the right here. Fromm a business standpoint, the school gets customers (parents) because they hold their staff and students to a specific moral code. If a teacher breaks that code, and they don't fire her, then they aren't giving the service that they said they were, and thus would lose customers.