It seems the teacher and principal need a conference on Christianity. They need to learn about Christian symbols and their meaning so that they can be inclusive and support students coming from a Christian heritage. (not sarcasm)
Yes, why do we never, ever hear of “sensitivity training” and educational sessions for those who offend Christians? Why is it okay to attack a child and possibly scar him for life if that child is a Christian? The PC crowd will have people fired and sent to sensitivity training who use words like “niggardly”, the meaning of which has nothing to do with a racial epithet. But they will justify the overreaction because the word is close to the epithet and someone may have been “offended”. Truly some animals are more equal than others.