If you're going to teach about one religion you have to teach about them all, it seems like keeping up with learning about all of the religions would be a bit difficult but I don't see why it couldn't be done.
If schools want to teach about religion, then so be it. Nobody will be harmed. This is not schools requiring children to try dangerous drugs or forcing them to fight tigers every week. It is more knowledge for them, and knowledge is good. Even more if it is religious knowledge, as it will help end this ignorance about what a religion is, ending the irrational fear of religions that is rampant today.