Sombrely, steadily and with a stoicism that has shown the best in its citizens, London has begun to return to normal. The Underground, the symbol of the city’s vulnerability, is running again — with increased vigilance and a reassuring police presence. The magnificent efforts of the emergency services continue, although the task of recovering the bodies from the wreckage in the deep tunnel near King’s Cross is slow and dangerous.

The meticulous examination of the remains of the bus blown up in Tavistock Square has begun with all the methodical expertise for which British forensic scientists are renowned. In time, they may be able to assemble enough evidence to give a more precise indication of the likely perpetrators of these crimes. They will never, however, be able to explain a mentality and motivations more twisted than the wreckage left by the bombers.

One question being urgently asked is whether the terrorists were recruited within Britain or slipped into this country from abroad. Both scenarios have worrying implications. If al-Qaeda, or any of the amorphous groupings sharing its nihilist ideology, has managed to infiltrate “sleepers” into Britain, the Security Service has suffered a considerable setback. This would suggest that the global terrorist networks have better survived the raids, killings and arrests in Pakistan, the Middle East and Afghanistan than had been presumed.

If the terrorists are home-grown, it has to be asked what degree of alien-ation, fanaticism and self-hatred has now gripped a minority of Britain’s Muslim community that young people — perhaps educated — should become willing recruits or even suicide bombers.

Their actions have, rightly, been forcefully condemned by all mainstream Muslim organisations. More than this is needed, however. At present, there seems to be a notion, adopted by bullying radicals, that extremism in religion is praiseworthy and intrinsic to Islam. This narrow, intolerant view quickly leads to the fanaticism that spawns the kind of evil movements that crystallise hatred and glory in a cult of violence and suicide.

For it is, indeed, a cult. Al-Qaeda, the Taleban and other politically extreme movements preach neither joy, nor love, nor light, nor certitude, nor peace, nor help for pain. There is nothing but misogyny, misanthropy, homophobia and mispaced machismo. Like Matthew Arnold’s vision of a world without faith, they leave their followers “Swept with confused alarms of struggle and flight/ Where ignorant armies clash by night”.

Muslims can find, instead, plenty to delineate their faith as one of tolerance, learning and justice. They have only to look in the Koran at sura (chapter) 2.256: “Let there be no compulsion in religion; truth stands out clearly from error.” Or they should heed the words of the Prophet Muhammad: “The true Muslim is the one who hurts no one by word or deed.” And such tolerance found its apotheosis in Muslim Spain or the Baghdad of the Abbasids — golden ages, to which Muslims today rightly look back with pride.

Intolerance, however, is seen, especially by some young people, to bring greater rewards in a materialist and selfish age. The response should not be an intolerance of those minorities within Britain, only an intolerance of intolerance.

Britain is at its best when it demonstrates, in its daily routine and lives, the values of humour, moderation, reasonableness and imperturbability. These were the qualities obvious to the outside world as it watched with horror the events unfolding in London. For some, especially for those in Madrid, the attacks brought back emotional memories of what happened in Spain. The reaction there had been a spontaneous demonstration of defiance by huge crowds linking hands and marching. Britain’s way has been different, but no less defiant. London went about its business, as much as usual. Terrorism will not defeat a way of life.

This weekend, Britons have a chance to remember this same message that brought us victory in the world war 60 years ago. Then, too, tolerance and freedom were threatened. Remembrance and gratitude should mark these special ceremonies in London to mark both VE and VJ-Day in a way that does not provoke new controversy but reminds a younger generation of the heroism and endurance of their grandparents. Britons should make an effort to attend and to show abnormal strength by embracing normality.