By Frank Gardner
BBC Security Correspondent
Al-Qaeda's violent methods and tactics have been coming under mounting criticism this year from Islamist scholars who once supported it.
Osama bin Laden's defiant message has inspired many Muslims
One by one they have been coming out in public to denounce the organisation's actions as being counterproductive.
But at the same time, a leading British de-radicaliser says the number of young British Muslims attracted to violent extremism is growing - and, he claims, the UK government is partly to blame.
In the living room of his London home, the Libyan former jihadist Nu'man Bin Othman reads out part of the open letter he sent recently to al-Qaeda's no 2 and chief strategist, Dr Ayman al-Zawahiri.
He tells him that al-Qaeda's tactics have been a failure and - most damningly - its methods un-Islamic.
He even questions its very claim to speak for Muslims.
Comrades in arms
What is so striking about this is that Bin Othman is no armchair commentator, he is a former comrade-in-arms of Osama Bin Laden.
Together they fought the communists in Afghanistan in the 1990s and as recently as the summer of 2000 he attended the al-Qaeda leader's 'summit' of jihadists in Afghanistan.
Yet now, while like many Muslims he still deeply disapproves of western policies and actions in the Middle East, Bin Othman is telling his former allies that al-Qaeda's strategy of apparent indiscriminate killing is wrong.
"I said to him, we want to give you what you need, not what you want. You need to re-examine your ideology and you need someone to advise you. Why should I believe I have a duty to support al-Qaeda? How, Islamically, did they establish their authority?"
His denunciation of al-Qaeda follows another highly significant repudiation by the jailed Egyptian ideologue, Sayyid Imam.
Also known as 'Dr Fadl', he is seen as the godfather of jihadi thought, the man whose edicts al-Qaeda's leadership have drawn on for years.
But last November he published a devastating treatise that drew on Islamic law and jurisprudence to plead with would-be jihadis that resorting to violence is forbidden, and so was rebelling against a Muslim ruler.
It said: "Oh, you young people, do not be deceived by the heroes of the internet, the leaders of the microphones, who are launching statements inciting the youth while living under the protection of intelligence services, or of a tribe, or in a distant cave or under political asylum in an infidel country.
"They have thrown many others before you into the infernos, graves, and prisons. Those who have triggered clashes and pressed their brothers into unequal military confrontations - are specialists neither in fatwas nor in military affairs."
So, are words like these having any effect on impressionable young men who are vulnerable to being influenced by al-Qaeda's recruiters?
To find out, we visited the Active Change Foundation in East London.
It's a movement set up to try to steer young men away from violent jihad. It was set up by Hanif Qadir, himself a former jihadi who turned back six years ago on the brink of going to fight alongside the Taleban in Afghanistan.
I asked him if all this ideological debate on jihadism is making any real difference at street level.
Many still want to take part in violent jihad, says Hanif Qadir
He replied that while some 'veteran' jihadists were coming back from theatres of conflict like Afghanistan and Chechnya bitter and disillusioned, the number of people queuing up for violent jihad was growing.
He blames western foreign policy for playing into the hands of jihadi recruiters and says the UK government should do more to listen to Muslim grievances.
"I think there's a lack of communication and I think that until we get this individual involvement from politicians and ministers and other people to come down and in this safe space have a critical dialogue, we're going to get young people who are going to try to vent their frustration elsewhere," he said.
It is almost as if there are two separate tectonic plates, grinding against each other in opposite directions.
At one level there is the intellectual debate, the Arab thinkers within the jihadi movement.
These are the people who are standing back and questioning whether al-Qaeda's extreme methods aren't actually doing more harm than good to Muslims.
But then down at the grass roots level, things are moving the other way, because there are still growing numbers of potential recruits to violent jihad, including in Britain.
Often these recruits have only a shallow knowledge of Islam, and they are far less impressed by theological debate than they are by more day-to-day, down-to-earth factors like TV reports of western airstrikes on civilians in Afghanistan or the presence of US and British troops in Iraq.
With conflicts still raging in those two countries, and the Palestinian question unsettled, it is still too early to predict with any certainty which way al-Qaeda's fortunes will go.
Frank Gardner reports on the future of Al-Qaeda in Analysis on BBC Radio 4 at 20.30 Thursday 7th August and 21.30 Sunday 10th of August. You can listen again or download a podcast from www.bbc.co.uk/analysis