To be elected as a member of parliament is as near as we get in these humanistic days to a sacramental role – ordained not by God but by us, the people. Each MP may be just another twig of Kant’s “crooked timber of humanity”, out of which “no straight thing was ever made”, but they each stand as the living representative of our right to choose who governs over us. For that reason, when they resign they undermine the sense of heavy obligation to their voters that they willingly undertook when they stood for election.

Jamie Reed has announced he is standing down from his Copeland seat to return to a job he prefers, back at Sellafield, his old employer. He has given the Guardian his reasons, among them that representing his large, scattered, mainly rural constituency, far from Westminster, means it’s “very difficult being a long-distance dad” to his four children.

Well, yes, it is. And he may have his personal reasons. But it always was a gruelling sacrifice, and this son of Whitehaven signed up for it, reconfirming himself in the role only last year in the general election. It is decadent and contemptuous of the democratic process to walk away, as you might from any ordinary job.

To be elected by the people is no ordinary calling, for which reason I have always emphasised that a certain measure of respect is due to MPs, even the ones I detest, against the dangerous tide of contempt for their calling.

How odd, it seems to me, is the reverence we have for “democracy”, willing to impose it on other countries at the point of a gun, and yet the office-holders of democracy are held in even lower esteem than journalists.

Whatever cynical old Westminster hands may say, I am still struck with awe each time I enter the cathedral-like Houses of Parliament: the stones of Westminster Hall have a very particular smell of history. The statue of Cromwell outside stands guard, along with Simon de Montfort on horseback. Yes, it’s an absurdly kitsch pastiche of a building, and the history of the long march to an infuriatingly inadequate form of democracy can be over-romanticised. But nonetheless, don’t take it for granted. Pause for a moment to consider the fate of the billions who are without the freedom to throw the bastards out.

There have been several frivolous or vainly self-publicising byelections, expensive and irritatingly pointless. It was good to see Zac Goldsmith get his comeuppance for a silly gesture. David Davis deserved, but didn’t get, the same for his quixotic resignation and re-election over civil liberties – though he now seems perfectly happy to sit in a cabinet trying to force through the snooper’s charter. The resignation of the little-known Tory MP Stephen Phillips was an utter mystery, since he had just stood last year on a manifesto he now purports to find repugnant, as he returns to his lucrative lawyering.

Jamie Reed has every reason to feel miserable about his fate as a Labour MP right now. Politics is a rough trade that eats many or most of its practitioners. Clever people who could achieve much more in the world outside give up all else to sit on the backbenches for most of their career, large slabs of it with their party out of office. Even if they make it, briefly, to become minister-for-obeying-your-senior-minister, even if they make it briefly to the cabinet, the chances are they will end their careers unable to point to any one thing they did that wouldn’t have happened without them.

Some do. Barbara Castle’s lifesaving 70mph speed limit; Patricia Hewitt’s smoking ban; Harriet Harman’s childcare and nurseries; Roy Jenkins’s great 1960s “permissive society is a civilised society” reforms; or David Steel’s Abortion Act. But personal achievements are few.

And Reed’s fate is faced by many Labour MPs. He’s a remainer in a 62% Brexit constituency. He has been a vitriolic opponent of his leader, resigning a minute after Corbyn’s re-election this year. He is pro-nuclear, the vital industry for his constituents, who are looking angrily at a Labour party led by an anti-nuclear campaigner. His seat boundaries will be redrawn, obliging him to fight with next-door Sue Hayman, Labour MP for Workington.

That’s a nasty nexus of wicked issues. But maybe he resigned to embarrass Corbyn, hoping finally to persuade the leader’s deluded followers that Labour is destined for a defeat so devastating it might be terminal. This marginal seat may easily be lost to the Tories or even Ukip. But think what harm that does, either giving Theresa May a much needed extra seat to bolster her narrow Commons majority – or, even worse, giving Ukip immense new credibility that will do great damage.

Labour MPs are being tested as never before. Reading the abuse directed at Reed from the left – “I always thought he was a Tory”; “He’ll be happier destroying the planet”; and much worse – it’s fair to say his own venting against Corbynism has also been pretty savage. But who would want to spend their life in that toxic zone of hatred and rage?

The answer is, those who chose to stand have a duty to stay and fight – for their party’s future, for their constituents against the worsening cuts, and for the country in its hour of extreme Brexit peril.

There are rumours others may follow Reed out of the door, but they must each find their own path to navigate through the thickets. To be true to their constituents, this means finding the bravery to be honest with them about the Brexit dangers ahead and the need for compromise. Many elected in Labour’s easy years are having to learn late in life what it takes to stand up and fight, not cut and run, when the going gets tough.