Does the ideology that animates Islamist terrorism have much, if anything, to do with Islam or with the great majority of believing Muslims? Or has it, as Lord Meghnad Desai suggested last week (Letters, August 10), no more relevance to Islam than Catholicism has to the IRA? Irish Republican Army? The answer to the latter proposition is a forceful “No”.

Lord Desai suggests, rightly, that contemporary Islamism is a modern revolutionary ideology. It is, in this way, socially and psychologically similar to communism. It propounds, as communism did, the thesis of a promised paradise – in this case a restored caliphate, instead of the socialist idyll. It suggests, as communism did, that this paradise would take the form of a perfect community – in this case for believers instead of for workers.