Democracies need an unloveable press, according to Michael Schudson, Professor of Journalism at Columbia University. Journalists are meant to speak truth to power, to avoid dependence on official sources, and to ask difficult questions. In many ways, they are to secular democracies what the Old Testament prophets were to ancient Israel. But perhaps it is evidence of a failing capacity in our culture to tolerate what we do not like, let alone love, that the BBC's political editor, Laura Kuenssberg, has faced months of abuse over Twitter, resulting in her requiring special protection as she reports on the Labour party conference.

Kuenssberg has faced online abuse for the past 18 months for appearing to be biased against Jeremy Corbyn. Indeed, in January this year, the BBC Trust found that her report on Corbyn's views on shoot-to-kill policies breached their impartiality and accuracy guidelines. Yet even the decision to assign Kuenssberg a bodyguard has precipitated backlash against her on social media. Criticism of a journalist's integrity and death threats hardly exist on the same spectrum. Moreover, Kuenssberg is not exactly the most contentious figure in the field of journalism. So, why the fuss?

Some commentators have suggested the fact that Kuenssberg is the first woman in her position explains the hostility towards her. Yet her detractors are by no means all men. Instead, I want to suggest that this incident is symptomatic of a wider issue: the decline of civil speech and a thinning out of the concept of tolerance. We might want to point the figure at social media in this respect. After all, screens provide a sense of invulnerability, and make it easier to dehumanise anyone with whom we disagree. We may refer to 'trolls' as if they were a group set apart, prone to thoughts and speech that we would never consider. But in reality, the lines are never so neatly drawn. We are all wont to treat people as Others, judging them by a standard to which we don't hold ourselves accountable. Jesus pointed out as much in Matthew 7:2.

Social media also enables us to surround ourselves with the voices of those who think like us, producing what has been called the 'echo chamber effect'. Few of us follow journalists who come from perspectives that differ from our own, and when we see our Facebook friends 'like' the same articles we do, we can easily conclude that all reasonable would think like us. Kuenssberg's crime, then, may be the fact that she works for the BBC: one of the few news sources we can expect to encounter no matter how we curate our social media news feeds.

And so we arrive at the issue of tolerance. If Aristotle was right that tolerance is the last virtue of a dying society, we should perhaps be concerned that there is no greater sin in today's society than intolerance. And yet, at the same time, we have cases like that of Laura Kuenssberg where hundreds of well-educated social media users attempt to silence a voice which is not a perfect echo of their own. Tolerance, in its 17th century meaning, referred to the ability to live alongside those whose religious views differed from one's own. With roots in the virtue of fortitude, it meant steadfastness, the ability to endure something. In other words, tolerance required sacrifice. One tolerated another at a cost to one's own comfort. As such, it was considered a Christian virtue in line with Paul's counsel to the Philippian church to imitate Christ's willingness to sacrifice privilege for the sake of others and 'in humility count others more significant than yourselves'. Social media and self-sacrifice, however, are not comfortable bedfellows.

Facebook used to encourage us to think in terms of like/ dislike, now broadened to a wider range of emoji reactions. Above all, then, we expect to engage in public debate as emotional actors – the stronger the emotion, the greater our right to participate. Perhaps things would be different if default reactions to social media posts included 'a point well made, even though I disagree' or 'I'm not sure your conclusion logically follows from your premise'. By no means should emotions be shut out from public debate, as the Enlightenment philosophers would have held. But for democracy to function, we need critical thinking. And for society to hold together, we need to be able to associate with, and listen to, those with whom we differ.

So why the cultural hypocrisy, extolling tolerance even as it is disdained? The answer, I believe, lies in what Nancy Pearcey in Saving Leonardo calls the fact/value dichotomy. Since the Enlightenment, moral values have been judged to be of a different sort of knowledge to that of 'objective' scientific fact and only the latter granted a space in the public sphere. This ability to hold whatever views one likes, if only in private, may seem liberating, but Pearcey cautions us that it is anything but. With no 'universal yardstick to measure private taste', which 'is not open to rational persuasion', 'all that remains is power and coercion ­­– each group seeking to impose its own preferences on others'.

Online abuse is perhaps the most common way we see that power being used as anyone with a voice on social media can take it upon themselves to be judge, jury and censor. Laura Kuenssberg is simply the latest victim of the death of tolerance (of other people's views) in the name of tolerance (of one's own)