Is my teacher out of line?

Now firstly I would like to point out that me and my ICT teacher do not have a good relationship anyway. And I don’t want people going “you’re a spoilt brat” or something, but I just wanted other people’s opinions on this.

A while ago I was in class, my friends were swearing loudly and the teacher wasn’t doing anything at all, except occasionally quietly going
“can you not use that language please?”
they continued.
In frustration at the work I went
“Jesus Christ!”
Now I said that in a completely none-offensive way and quietly just to myself. But as my teacher heard it was me, she went
“NO BLASPHEMY!!!”
Loudly so that the rest of the class could hear.
This made me particularly angry, mainly because we don’t go to a religious school.
She is a christian fair enough, but I don’t think that should really come in to it. Especially since it’s not her who would be going to hell for it, it would be me.
Does anyone agree in that she should have definitely focussed more on the swearing rather than me?

I am an Agnostic atheist just for the record.