For decades now the United Nations has been unable to agree a definition of terrorism. Even our own supreme court recently concluded that there is no internationally agreed definition. The stumbling block has been that western governments want states and state agents to be exempt from any definition. And a number of Islamic counties want some national liberation movements exempt.

Or, to put it in terms of today’s news: the Israelis won’t have any definition that would make them terrorists for bombing old people’s homes in Gaza, and West Bank Palestinians won’t have any definition that will make them terrorists for fighting back against occupation with petrol bombs. Writing in his annual report this week, David Anderson QC, the government’s independent reviewer of terrorism legislation, sounds exasperated: “The intractability of some of these questions has induced a degree of defeatism among those seeking to define terrorism.”

I am eating aubergines and flatbread with Dr Samah Jabr in a cool Palestinian cafe in Stoke Newington. A psychiatrist and psychotherapist who works out of East Jerusalem, Dr Jabr is quietly spoken, modest, and perhaps just a little bit shocked by my lapses into overly colourful language. She is an educated, middle-class Palestinian (in no way a rabble-rouser) but she insists that the word terrorist has become a powerful – though often un-thought-through – political pejorative employed to discredit legitimate resistance to the violence of occupation.

What some would call terrorism, she would call a moral duty. She gives me her paper on the subject. “Why is the word ‘terrorist’ so readily applied to individuals or groups who use homemade bombs, but not to states using nuclear and other internationally proscribed weapons to ensure submission to the oppressor?” she asks. She insists that violent resistance must be used in defence and as a last resort. And that it is important to distinguish between civilian and military targets. “The American media call our search for freedom ‘terrorism’,” she complains, “despite the fact that the right to self-determination by armed struggle is permissible under the UN charter’s article 51, concerning self-defence.”

I took part in the Moral Maze recently on Radio 4 and was howled at for suggesting that there could be a moral right of resistance to oppression. And the suggestion was made that, as a priest, I ought to take no such line. The weird thing about this is that Christianity has thought a great deal about the idea of just resistance. The Reformation, for instance, saw a flurry of moral justifications for resistance to the state, when that state is seeking to impose on its subjects its own particular understanding of religious faith. In 1574, for example, Theodore Beza published his The Right of Magistrates in which he affirmed the right of resistance – and violent resistance in the final instance – to state tyranny. This sort of thing was hardly a one-off.

Indeed, so much of our modern political theory about the role and limits of the state was established by the political theology of the 16th and 17th centuries – and by those who would be branded terrorists under this country’s current terrorist legislation. Oliver Cromwell, for instance, would almost certainly be a terrorist. Come to think of it, so too would Moses and his famous (and very violent) run-in with the Egyptian state. And both of these were “religiously inspired”. If we can have just war, why not just terrorism?

It is nonsense to think that being a state grants some sort of blanket immunity from the charge of terrorism – and certainly not from the moral opprobrium we attach to that term. We talk of asymmetric warfare. This is asymmetric morality: one that, in terms of the Israel-Palestinian conflict, loads the dice in favour of the occupation. This is just not right.

Twitter: @giles_fraser