也理解老师，但是感觉老师的措辞不妥，论点站不住脚，

要让5岁小孩明白＂CANNOT tell other people what they can and cannot believe in.＂，这要求太高了写吧。看完信的感觉是，这信颇有些宗教色彩哦，圣诞节是个宗教节日，老师显然不喜欢＂异类＂分子＂搞破坏＂。还有，按照老师说的，你儿子不可以＂tell other people what they cannot believe",那么其他孩子和老师在讲＂Santa this Santa that"的时候，是不是在＂tell other people what they can believe"呢？

告诉你儿子，there are some truth that you don't have to tell everyone if not asked.