Former British prime minister Tony Blair warned Sunday that the Islamist ideology allegedly behind the murder of a British soldier in a London street was "profound and dangerous".
Blair, now an international Middle East peace envoy, said it was time to admit the breadth of a "strain within Islam" harbouring views incompatible with free societies.
Blair, a Roman Catholic who says he reads the Koran daily, said most Muslims in Britain would be horrified at the murder of Lee Rigby on 22 May.
"There is not a problem with Islam," he wrote in The Mail on Sunday newspaper.
"There is a problem within Islam -- from the adherents of an ideology which is a strain within Islam. And we have to put it on the table and be honest about it.
"I am afraid this strain is not the province of a few extremists. It has at its heart a view about religion and about the interaction between religion and politics that is not compatible with pluralistic, liberal, open-minded societies.
"At the extreme end of the spectrum are terrorists, but the world view goes deeper and wider than it is comfortable for us to admit. So by and large we don't admit it."
He said that made Islamic extremists think "we are weak", which in turn makes those within Islam who want to tackle the issue "lose heart".
The former Labour Party leader said revolutionary communism was resisted by being resolute on security, "but we defeated it by a better idea: freedom. We can do the same on this.
"The better idea is a modern view of religion and its place in society and politics.
"Religion must have a voice in the political system but not govern it."
Blair suggested that the "problem within Islam" could start to be tackled by "educating children about faith".
Two men charged with murdering Rigby are due to appear in separate London court hearings on Monday.
Michael Adebolajo, 28, who has also been charged with the attempted murder of two police officers and possession of a firearm, was to appear before Westminster Magistrates' Court.
Michael Adebowale, 22, also charged with possessing a firearm, was due to appear for a bail application at the Old Bailey central criminal court, ahead of a pre-trial hearing on 28 June.
Both Muslim converts of Nigerian descent, they were shot by police at the scene of the killing near Rigby's barracks in Woolwich, southeast London.
An inquest into Rigby's death heard that he was run over by a car before being attacked by two men armed with a cleaver and a knife.
Adebowale made his first court appearance on Thursday, speaking only to confirm his name and address before being taken back into custody.
The murder is the first fatal Islamist attack in Britain since suicide bombers killed 52 people in the London transport network in 2005.