The 20th century witnessed death on a mass scale, often consciously directed at specific ethnic, cultural and religious sectors of national populations. These crimes against humanity were of a kind that required a new name - genocide.
It was genocide that was on the mind of the newly formed United Nations when it made its Universal Declaration of Human Rights in the form of 30 articles on December 10, 1948. But by the end of the 20th century there had been a massive failure by the international community in preventing a repetition of the historical scars that marked the early and middle part of the century.
Harsh historical truths present urgent questions for teachers of religious education and citizenship. What does violence on a systematic scale directed at religious or ethnic minorities do to change our understanding of citizenship? Does genocide make notions such as civilisation and citizenship a veneer, and the hopes of religion a matter of wishful thinking? Citizenship is still seen by many religious educators as contentious, and not only for crowded curriculum time.
Citizenship covers all aspects of a person's political and religious, social and cultural identity. It is this breadth that provides the common ground with religious education, and the potential for conflict.
Ironically, the Qualifications and Curriculum Authority's unit 13 scheme of work on citizenship and RE(www.qca.org.uk) focuses explicitly on conflict, highlighting historical and contemporary political arenas where religion remains a source of war and violence.
Not all religions have a good record on human rights when it comes to issues as broad as gender equality, freedom of expression, or even freedom of religion and belief. Often, religious fanaticism and democracy do not easily go hand in hand. The risk here is of another stereotype: that religion is the source of too much fighting and too many of the world's wars.
This negative image has been exacerbated since September 11, 2001. In an odd twist of fate the UN's World Conference against Racism, Racial Discrimination, Xenophobia and Related Intolerance had concluded on September 8 of that year, in South Africa, on a supposedly optimistic note.
However, ugly debates about the clash of civilisations soon re-emerged.
Religious education runs two risks: either it represents religion as inoffensive, or it confirms media stereotypes that religion remains a major source of conflict in the modern world. What teachers of religious education possess is the expert knowledge of religious traditions that can provide informed, balanced and engaging perspectives on identity, beliefs and values and what happens when these clash. At their most extreme, violently contended concepts of belonging can become crimes against humanity.
Questions of identity and conflict are directly relevant to life in the United Kingdom, with widespread public debates about what it means to be British. Negative headlines about asylum seekers and the Home Office's move to introduce a test on British citizenship (www.homeoffice.gov.uk) seemed to be tied in the popular imagination with the introduction of citizenship to the national curriculum.
What about UK citizenship? Many citizens of the UK have allegiances to their particular country (England, Scotland, Wales or Northern Ireland) and also to their religion; an allegiance that extends beyond national borders.
One form of allegiance does not need to exclude the other. Cultural and often religious identity will always remain important in defining a person's sense of belonging, and so too will their relationship to the country in which they live. It's what makes citizenship as a subject and as a concept so complex.
Without religious education many questions of citizenship, belonging and cultural identity are likely to be ill-informed. One thing is for sure: citizenship is not just about being a compliant member of society or a "good" citizen - it is more about offering an education for thinking, critical and questioning citizens who are able to deal with the issues that arise in a world where belonging and identity are far from simple.
Liam Gearon is reader in education and director of the Centre for Research in Human Rights at the University of Surrey Roehampton