First Hawklore, you already know the facts. Second, your teacher has probably revealed some bias, perhaps even an underlying hatred, by arguing you will not change her mind, only change her view of you.
However, if you feel strongly enough about it then you should ask her for proof of this statement. The only place she will pull such "facts" is from an anti-Catholic source, ie a hate-source. This would confirm her beliefs, and at that stage I'd kick the issue higher up the chain of command.