One of the defining characteristics of civilization is a commitment to understanding and learning from history. One hopes that this process will make it possible for real social progress to occur over time. But those who want to use history as a tool to advance their own interests actually work against civilization and promote the cause of barbarism:
Teachers [in the UK] are dropping controversial subjects such as the Holocaust and the Crusades from history lessons because they do not want to cause offence to children from certain races or religions, a report claims.
The report, produced with funding from the Department for Education, said that where teachers and staff avoided emotive and controversial history, their motives were generally well intentioned.
“Staff may wish to avoid causing offence or appearing insensitive to individuals or groups in their classes. In particular settings, teachers of history are unwilling to challenge highly contentious or charged versions of history in which pupils are steeped at home, in their community or in a place of worship,” it concluded. [my emphasis] — Times Online (UK)
Pay attention to the last paragraph, whose implication is the following: history teachers are simply afraid to talk about these subjects because they face retaliation from Muslims who insist on their right to teach their children, for example, that the Holocaust was invented by the Jews.