Acclaimed war correspondent Rageh Omaar examines the effect the Crusades have on the world today. In the West, the Crusades are a chapter of Christian history that has little impact on our everyday lives, but in the Middle East many believe that the Crusades are happening again. In the wake of 9/11, President George W Bush described the War on Terror as a 'Crusade'. Rageh believes this invocation of Christian Holy War alienated much of the Muslim world. Bush's comments have never been forgotten and are today exploited by Islamist terror organisations, who refer time and again to the West as Crusaders. On his journey through Europe and the Middle East, Rageh speaks to historians as well as ordinary people in order to understand how it is that events of 900 years ago can have such a divisive effect on relations between the West and the Muslim world, and on two of the world's greatest religions - Islam and Christianity.

• Michael Portillo
• Cherie Blair