This is more common than you may think.  I was 1 of 4 Jewish kids in a large high school in eastern PA.  The amount of crap I took from teachers and/or administrators because I am not Christian was pretty damn frustrating.  That crap was everything from being sent to detention for not wanting to sing Christmas songs praising Jesus as a part of a required Christmas pageant, to being told pointedly that I would fail a class if I missed a day for the Jewish High Holidays.  Those holidays happen early enough in the school year that there is no way I wouldn't be able to make up the work, but since the teacher had scheduled a test for that day, with no way to make it up, I was out of luck as far as he was concerned.  Thankfully, my parents are both incredibly pushy and managed to make most of the problems go away without resorting to suing.

As for the Christmas songs, I would have been fine if they had been the secular Rudolph and Santa type songs, but not full on religious ones.