The exact relationship between mainstream, tolerant, peace-and-love Islam and extremist, intolerant, war-and-hate Islamism will doubtless be disputed for years to come.
What can't be disputed is that the darker, fundamentalist parts or offshoots of the world's fastest growing religion continue to cause Britain and the West huge problems - and expense.
Truthfully, when you see the word 'Islamic' in a news headline, do you not brace yourself?
Why so? Is it latent 'Islamophobia'? Or prior knowledge of horrors perpetrated in the name of Islam?
When it's not terrorism, it's radical preaching in mosques or schools, or Pakistani Muslim rape gangs, or isolationist ghettos coalescing around huge new mosques, or young men and women running away to join ISIS, or Jews and homosexuals fearfully avoiding Muslim areas.
Frankly, we're sick and tired of it all.
We acknowledge, of course, that the decent majority of Muslims are as distressed by these things as we are, that troublemakers are a minority.
But the fact is that Britain can't keep paying the huge (and growing) costs incurred by these darker elements.
For example, Shamima Begum and the other 'jihadi brides' now pleading to return from war-torn Syria.
Begum is a young woman, an unrepentant ISIS supporter.
• If she comes back to Britain, how many £ millions will it cost to monitor her for the rest of her life? Or to monitor hundreds of other returning jihadists and jihad enablers?
• How much will it cost taxpayers to monitor the 20,000+ suspected jihadists already here (assuming the government can ever be bothered to do so)?
• How much will it cost to incarcerate fundamentalist criminals, and to segregate them from others to prevent the spread of their virulent ideology? (Muslims make up 15 percent of the prison population but five percent of the general population.)
• How much will it cost to monitor indefinitely all the mosques and schools in Britain suspected of extremist teaching?
• How much will it cost to police pro-Sharia, anti-Western demonstrations organised by the likes of Anjem Choudary, recently released from prison?
• How much will it cost to identify and prosecute the scores of suspected groomers and rapists who've preyed on young English and Sikh girls with impunity for decades?
• How much will it cost to integrate Muslim ghettos into the mainstream - assuming this is even possible?
• How much will it cost to keep a lid on rising inter-communal tensions through publicly financed 'community cohesion' initiatives, 'inter-faith dialogues', and all the rest?
• And how much will it cost to continue prosecuting and jailing citizens who speak robustly about Islam's dark side?
These are just some of the financial costs British taxpayers are expected to bear.
As for the human and societal costs of Islamist extremism, and the erosion of free speech due to 'Islamophobia' hysteria - these are incalculable.
We ask the government again: how much will Islam cost?