Of course Jewish pupils have time off for religious holidays. I have taught such children and they present me with a letter from the parents at the beginning of the school year listing the days the child can't attend. These days are recorded as absences. The family don't expect school life to be altered for them in any way. But there is a world of difference between that and asking for exams to be moved for all pupils. I trust you will be able to supply the names of the schools where birthdays and Christmas weren't celebrated to the TES moderators. I find it impossible to believe this happened unless most pupils belonged to the same church. Having taught Jehovah's Witness children, they don't celebrate their own birthdays or Christmas but again they wouldn't expect the life of the school to be changed to suit them.