A teenybopper concert in Manchester. A tourist day in Westminster. And now a Saturday night of revelry in central London.

Enough is enough, says Theresa May: there is “far too much tolerance of extremism in our country”. She’s right. “It will only be defeated when we turn people’s minds away from this violence and make them understand that our values, pluralistic, British values, are superior to anything offered by the preachers and supporters of hate.”

Right again. I hope now she’ll also take active steps to address the rampant intolerance – at odds with those British values – that has riven society over the past year of poisonous politics. There is a lesson to be drawn on this tragic day, with seven dead, 48 injured and hundreds of lives forever changed: we either beat the killers and cowards together or not at all.

In the aftermath, we can also see that the targets for this recurring horror have assumed a definable pattern. They are soft targets. We can send armed guards and security scanners to government installations, but how can any pub or any concert foyer in any city be made bomb- and attack-proof?

They are sudden. No warning telephone calls, no coded messages, no tacit understanding. It feels as if the terrorism of years gone by was played out under Queensberry rules.

There is no obvious or significant ambition to destroy the pillars of the state: the men who use cars and vans as weapons and strike at random with foot-long knives aren’t obviously seeking to obliterate army barracks or police stations or the Bank of England. Theirs is a war not on the foundations of a free society or on our vital infrastructure, but on people enjoying the benefits of a free society. It is, in many ways, a war on joy, motivated by a warped sense of piety.

How we work, how we play, they are two sides of the same coin

We go out and dance and drink and eat. To zealots, these things are decadent and trivial. Yet they are in themselves small acts of political symbolism: we go where we like, do what we like, wear what we want, we love whom we choose, because we have a social framework and a political system that largely allows us to do that. If the extremists cannot dismantle the system, or the foundations that underpin it – and they know they cannot – then they seek to strike and terrorise ordinary citizens who benefit from the gaiety it offers and the freedom it brings.

It is customary at these times for politicians and the police to redouble their efforts to keep us safe and to tell us to go about our daily business. Cressida Dick, the new Metropolitan police commissioner, struck the right tone, praising the emergency services and urging communities – all grieving – to cohere.

That resumption of normality is, in itself, a predictable and a necessary act of defiance. The shops that open quickly, the trains and buses that run, the commuters who commute: each one makes a statement. These are the essentials that make society work. We will always maintain them.

But there is a bigger danger, and it is that we now start to think twice about the things that bring joy – the night in a pub or a music-filled bar or club, the evening of shared experience in a public place, the mass sporting events, the standing-room-only concert halls, the shopping malls, the cinemas, the theatres – the many experiences that give life texture and richness. The risk in those places isn’t likely to disappear any time soon, for they seem to encapsulate everything the murderers hate. But the risk will always be minimal; we are going to have to price it in. How we work, how we play: they are two sides of the same coin. Even at a time as painful as this, the biggest risk is that we let the zealots rob us of what makes us who we are.