International development aid is the latest casualty in the Brexit war of words. Rightwing zealots are now arguing not just for our £14bn aid budget to be redirected to spending at home but also for the abolition of the Department for International Development and the redefining of aid “as we see fit”, with what’s left no longer there primarily to help the world’s poor but to project their own view of British nationalism on to the world stage.

As if comparing overseas aid to the work of a modern Mrs Jellyby, whose eyes, according to Charles Dickens in Bleak House, were fixed on “nothing nearer than Africa” while she neglected her own children at home, the right now caricatures aid not only as inefficient, wasteful and a way of the poor in rich countries subsidising the rich in poor countries, but also as money diverted to dubious causes abroad from good causes at home – the insinuation being that sending British money abroad to people who are not British is in some way unpatriotic.

When these neoliberal ideologues tell us ‘charity begins at home' what they mean is that charity begins and ends at home

So when these neoliberal ideologues tell us “charity begins at home” – an aphorism which originally meant charity is first learned at home – what they mean is that charity begins and ends at home, and that we need feel no obligations to the rest of the world. So don’t believe for a moment the Brexiteer contention that “we are leaving Europe to join the world”. Their descent into an introverted, selfish each-nation-for-itself nationalism has gone so far that many of the same people who want to secede from Europe want to secede from long-standing international institutions such as Unesco too.

It saddens me that Theresa May has now offered us the global version of Margaret Thatcher’s view that there is no such thing as society, only individuals; namely that there is no such thing as global citizenship, only individual states. The insularity and bleakness of this view of human nature would astonish the right’s intellectual leaders, from Adam Smith to Winston Churchill, whom they cite as their inspiration. Smith did indeed ask why it was that what he called “the man of humanity” would be unable to sleep if he suffered a small cut to his own finger, but would sleep soundly even as a million Chinese died in an earthquake. But his answer was not to argue that we were self-seeking individualists justified in being out only for ourselves, or that we were narrow nationalists. Instead he argued the opposite: that we were all part of a circle of empathy; that we could indeed put ourselves in other people’s shoes; and that with better information, education and communication, our concern for others would flow outwards from family and nation to include the wider world.

So for Smith there is no contradiction between empathy for the poor at the end of our street and the poor at the other end of the world: we can feel, however distantly, the pain of others; and we do believe in something bigger than ourselves.

So when we ask “who is my neighbour?” we do not just mean a neighbourhood of a few local streets nor confine ourselves to the UK but are including the very people whom the UK aid budget helps, and whom so many other great international organisations support – not least the 10 million impoverished African and Asian children who, because of our direct help, can go to school this week, and the many millions of children who are being vaccinated and protected from formerly lethal infectious diseases.

When we talk of community as a good, we are not just describing small, local enclaves, but a network of relationships that today, at the touch of a screen, can potentially link us to almost anyone anywhere in the world. And when we ask what is citizenship in the modern world, we mean not only legal status within a state but a wider set of obligations that we owe to each other by virtue of our common humanity, including our shared responsibility for our small and now unsustainable planet.

Across history, this is what it has meant to be British: not inward-looking, detached from the world and glorying in isolation – the view of Britain favoured by extreme Brexiteers – but outward-looking, internationally minded and long engaged with the world beyond our shores. And so when we support aid to the poorest people in the world’s poorest countries we are not giving up on the poor in Britain, downplaying or sidestepping our responsibilities to the people of Britain, but demonstrating yet again what it is to be British and doing so for a modern, interdependent world.

And when we consider what lies behind the Brexit impasse, might its root cause not be that these two ideas of what it is to be British are competing against each other, and until we can reconcile these two world views we cannot move on? I worry about a definition of patriotism that implies we are best on our own, sufficient unto ourselves – almost glorying in isolation. It is sometimes characterised by an appeal to what is interpreted to be the Dunkirk spirit, but in fact we stood alone not out of choice but out of necessity.

And while Brexiteers claim they are rediscovering our true spirit as a nation, they are, in my view, disowning our greater, far more powerful internationalist history as a country – a nation of explorers, missionaries, traders, merchant venturers, international diplomats and now NGO leaders who have always seen the English Channel not as a moat cutting us off but as a highway that connects us to Europe and the wider world.

It may be that this Brexit divide is so deep, so pervasive and so entrenched that it could take a generation for our country to resolve these differences and fully recover a unifying sense of purpose and direction. But I am absolutely sure of one truth I take from our history – one that has been sadly absent from our political discourse during and since the referendum – that we will regain our confidence as a country when we rediscover that to be truly British is to be outward and not inward looking, internationally engaged and not disengaged, generous-minded at home and abroad, guided far more by empathy and far less by prejudice, and true to ourselves, our communities and the world.

• Gordon Brown was UK prime minister from 2007 to 2010; this article is based on a speech made to mark the launch of Christian Aid week 2019