If there's one point of agreement about Syria and the latest atrocity there – the chemical weapons attack on Douma, in eastern Ghouta – it's surely that everyone is utterly sick of politicians' platitudes.

We have had enough of people telling us it's unacceptable. Enough of calls for a ceasefire, for dialogue, for negotiations, for sanctions. Enough denunciations from the pope, the archbishops, the World Council of Churches. Enough referring it to the UN.

All these things make people feel better, but they don't stop the killing. This is because at the head of the Syrian government is a man who does not care what people think of him and what people say. He knows he can do what he wants, and that the people who could stop him won't do so because they are weak and cowardly.

The failures of the West in this particular case can be traced back to a vote in the British parliament in August 2013. More than 1,400 people were killed in sarin gas attacks in eastern and western Ghouta. Public anger was intense; a 'red line', as President Obama put it, had been crossed. The prime minister, David Cameron, put it to the house that a military response was called for.

In what was arguably the most shameful act of any parliament for generations, a combination of political opportunism, misguided idealism and moral cowardice saw him defeated.

The vote gave Obama the excuse he needed to remain quiescent. Nothing was done.

Cameron had argued that the gas attack was 'a humanitarian catastrophe, and if there are no consequences for it, there is nothing to stop Assad and other dictators from using these weapons again and again'.

He was right. Since then chemical weapons have been used repeatedly against defenceless civilian populations.

There is, for Christians, an enduring and irreconcilable tension between being people of peace and defenders of the weak. At one end of the spectrum there is the pacifist who believes all military activity is wrong. At the other is the Second Amendment devotee who believes the only answer to a bad person with a gun is a good person with a bigger gun.

Most of us live in the contested area in between. We abhor violence and wince at its glorification in military parades and at the rhetoric of conquest. But we know that wars sometimes have to be fought and we are reluctant to sacrifice the children of Douma on the altar of our tender consciences. We don't want people to die in airstrikes. But we don't want people to die coughing up their lungs after a gas attack, either. And a point is reached where we cannot avoid the choice: where sanctions, threats and appeals have all failed because the perpetrator laughs at them, perhaps there are only two things left: do something, or do nothing.

There are times when doing 'something' is worse than doing nothing. The history of intervention is littered with examples. But doing nothing is a choice, too. It's not a way of washing our hands of the situation, Pontius Pilate-like. As the late Jo Cox – herself a former humanitarian aid worker – wrote in a Policy Exchange report from 2017 (The Cost of Doing Nothing: The Price of Inaction in the Face of Mass Atrocities): 'I still firmly believe that a legitimate case can be made for intervention on humanitarian grounds when a Government is manifestly unwilling or unable to protect its own civilians. Sovereignty must not constitute a licence to kill with impunity.'

If we feel at all responsible for what's happening in Syria – as fellow human beings, let alone as members of nations whose actions precipitated the catastrophe there – we must, at least, acknowledge that the choice is clear. If Mr Trump, Mrs May and Mr Macron opt for action we shouldn't wring our hands and wonder whether they're being too hasty. They are in office to exercise power, wisely and courageously, and most of us are thankful that we aren't in their place. 

There is, perhaps, an opportunity to say, 'Enough' to the use of chemical weapons, whatever other horrors might still be in store for the innocent victims of Syria. Has the West yet learned that inaction is a choice too?  

Follow Mark Woods on Twitter: @RevMarkWoods