It has been several days since the Manchester suicide attack which killed and injured joyful girls and boys, women and men who had just been to a pop concert. It's blame time folks.

When unpredictable events shake up a relatively secure nation, the responses follow a predictable pattern. Shock, pain, disbelief and sorrow are followed by high anxiety and discombobulation. Then come noisy, invasive speculations and questions, unfair generalisations. This was a bomb attack by a Libyan Muslim, therefore all British Muslims must be the enemies within.

Why does the Muslim community not condemn these terrorists? See what happens when we let in refuges from Muslim nations? It's all the fault of liberals, they who will not name and shame Islam. And so on.

I have, as a Shia Muslim, tried this week to explain to fellow Britons that we Muslims are not one monolithic community (how I detest that word 'community' and its false unities).

We are diverse peoples and individuals. Shias or Ahmadiyas- another Muslim sub-strand- do not become jihadis or suicide bombers. Those 'warriors' are found among Saudi-led Muslims – Wahabis, Deobandis and Salafis.

Honestly, I feel more able to communicate with Ukip voters or fundamentalist American Christians than with these anti-modernist, anti-female, intimidating, livid believers. Still, at moments like this, all Muslims are stained by the blood shed by violent extremists. It's just the way it is.

Today the story has moved on to accountability. Everyone wants to know if this savagery could have been prevented and whether there were lapses of judgement and derelictions of duty. This stage is important and necessary.

Let's take the more obvious failures first. Millions have been spent on surveillance, informers and undercover policing since the 2005 London bombings. Intelligence and interceptions have prevented a number of planned terrorist hits. But with this atrocity shows up an unacceptable level of negligence and professional malpractice.

Manchester Arena attack
Balloons, flowers and messages of condolence are left for the victims of the Manchester Arena attack Reuters

Our security services, police and counter-terrorism agencies were, it is claimed, repeatedly warned about the 22 year old suicide bomber, Salman Abedi. Sheikh Mohammad Saeed, Imam of the mosque Abedi attended told anyone who cared to listen that that the young man showed him a 'face of hate' after an anti-Isis sermon he delivered.

Years back, calls were made to the anti-terror hotline about Abedi's radicalised views; some of his relatives repeatedly raised concerns; two students who knew Abedi in college tipped off police officers about his support for suicide bombers; his own parents confiscated his passport a few months back. The killer got into the lobby of the Manchester arena without a security check. Now hyperactive officers are looking for Abedi's terrorist networks and other cells. Not good or soon enough. There must be a reckoning with those who failed the victims.

The family too is responsible for what happened, a stark line, but needs saying. Here they were refugees from Ghaddafi's Libya, presumably very relieved to have escaped from a country where no one was free, where torture was commonly used to cow and control the population.

Turns out the father, Ramadhan, who opposed Gaddafi, was committed to puritanical, political Islam. They had three sons and a daughter. Hashem, younger than Salman, was photographed as a boy with a gun. His dad was so proud.

Now, an engineering student in Tripoli, Hashem has confessed under interrogation that he knew about his brother's plans. The family moved back to Libya, leaving Salman behind. Though he visited them often, those who know him say, this abandonment hit him hard. He lost himself. He drank, did drugs, then became hysterically religious. He had physical fights, radicalised friends. He was a bomb waiting to go off.

And still his father refuses to accept what was done and says: "There are hidden hands that want to tarnish the image of Muslims who live in the west."

When I saw the statement, I wanted to shake the man out of his righteous complacency. Denial just adds to his sins of terrible parenting and even worse political and religious judgements.

Well-integrated Muslims must now take on, denounce and disable the Wahabi project. No more tolerance for the despicably intolerant.

Finally, to Saudi Arabia, generous sponsor of anti-western Islam and terrorist ideologies across the world. The Abedis are products and purveyors of that dark Islam. Instead of holding Saudi Arabia to account, the west genuflects before its oil wealth. Voters must now ask the parties what they will do to stop this evil empire.

Unless these steps are taken, we will not be safe. Manchester was a wake-up call.

Yasmin Alibhai-Brown is a journalist, columnist, broadcaster and author. Follow: y_alibhai