Most people think that politicians are liars, or they did last time I checked.

There is a sense in which this is manifestly false. Having worked with a good number of them I can attest that, as hard as the political game is played, most are full of a sense of personal integrity.

However, as philosopher Hannah Arendt observed: "Truthfulness has never been counted among the political virtues, because it has little to contribute to that change of the world and of circumstances which is among the most legitimate political activities." Her point was not that politicians were, in the sense of their own character, mendacious and habitual deceivers, but that politics and truth are antithetical. Politics is about creating convincing narratives - and facts are servants to that cause, not masters.

This week, Arendt's analysis has been shown again to be more accurate than we would like to believe. Take Nadine Dorries' attempt to amend the Health and Social Care Bill, seeking to establish the principle that women should be offered counselling from providers who do not also carry out abortions.

The amendment was soundly beaten in Parliament on Wednesday. True, Dorries' over-long, self-important speech did the amendment no favours (even a co-sponsor, Frank Field, decided to vote against it). But this is too harsh; she did not marshal the best arguments, but having the best arguments is clearly secondary to having the ability to command the most support for one's description of the situation.

Dianne Abbott - the Labour font bench spokesman who led the charge against the amendment (though there was no whip) celebrated "the absence of a Fox News pumping out socially conservative propaganda 24 hours a day". Indeed, the amendment was (in the end successfully) portrayed as an anti-abortion gambit from the 'Christian right', proof again that 'faith should be kept out of politics'. For Hadley Freeman of the Guardian, this is an example of British politicians 'adopting the Christian-right's anti women attitudes' and for Laurie Penny in the New Statesman, proof that a 'small, vocal and venal group of Christian conservative lobbyists' are rolling back women's right to reproductive choice. Whatever the amendment was, none of these are true descriptions.

Of course, what Arendt called 'organised lying' is practiced in all policy areas. In a stock Today programme or Newsnight interview, a politician tries to establish their description of the situation, the interviewer selects the facts which might puncture their description and puts them to said politician. The politician evades or ignores those facts, and throws in a contradictory selection. Meanwhile, we valorise transparency, freedom of information and evidence-based policy making and think that we thereby put ourselves at the service of the truth.

At a Theos lecture two years ago Stanley Hauerwas gave what at the time I thought to be an overly simplistic answer to the question: what should Christians involved in politics do? In the light of a growing realisation that our politics is configured by untruth, I now think his answer extraordinary:

When people ask me 'what is the primary role of Christians?', 'what should they do?', I have a very quick answer: don't lie. Try to say as accurately as you can what is necessary to know truthfully where we are. That is a very hard task; it's a very demanding business. We don't so much lie because we are motivated to do so… the lies speak us.

There is much more to be said on what speaking the truth might look like. In its own right, it can be an act of cynicism - like a habitual liar who knows that occasionally telling the truth can be a great way of misleading.

But Christians in public life have a choice - to become better at organised lying than others, or to learn what it is to speak the truth.

Paul Bickley, theos