The ideology which drives Islamic extremists has significant support from Muslims around the world, Tony Blair has warned.
The former prime minister said that unless religious prejudice in Muslim communities is rooted out, the threat from the extremists will not be defeated.
Speaking at the 9/11 Memorial Museum in New York, Mr Blair said that while the numbers who engage in violence through groups like Islamic State are relatively small, many of their views are widely shared.
"The conspiracy theories which illuminate much of the jihadi writings have significant support even amongst parts of the mainstream population of some Muslim countries," he said.
"There are millions of school children every day in countries round the world - not just in the Middle East - who are taught a view of the world and of their religion which is narrow-minded, prejudicial and therefore in the context of a globalised world, dangerous."
Mr Blair acknowledged that attacking ideas which resonate in parts of mainstream Muslim society could appear to be an attack on Muslims rather than just extremists, but he said such concerns have to be overcome.
"If large numbers of people really do believe that the desire of the USA or the West is to disrespect or oppress Islam, then it is not surprising that some find recourse to violence acceptable in order to re-assert the 'dignity' of the oppressed," he said.
"If young people are educated that Jews are evil or that anyone who holds a different view of religion is an enemy, it is obvious that this prejudice will give rise, in certain circumstances, to action in accordance with it.
"The reality is that in parts of the Muslim community a discourse has grown up which is profoundly hostile to peaceful co-existence. Countering this is an essential part of fighting extremism."