The evils which are perpetrated by modern witches exceed all other sins which God has ever permitted to be done.

The quote is from The Malleus Maleficarum, the infamous Hammer of the Witches: a massive tract compiled by two German churchmen in 1488 to provide the theoretical framework for the witch-hunts that raged across Europe during the early modern period.

According to the Maleficarum, a witch might destroy crops, eat a baby, or even “deprive man of his virile member”. But, if the”‘guilt of witches exceed[ed] all other sins”, that was not because of what they did, but because of why they did it. Irrespective of how much damage the witch actually caused to your field, she was still in the service of the devil. Her deeds, in other words, mattered less than her nature.

It’s easy to scoff at the superstition of a distant age. But a similar logic plays out in our attitude to terrorism today.

Last week Greg Sheridan, the influential foreign editor of the Australian, explained that “the gruesome terrorist murder of a member of the British armed forces in London should serve as a wake-up call to Australia.” [paywall] Specifically, the killing of Lee Rigby by two cleaver-wielding men in Woolwich meant that draconian anti-terror laws should be maintained, and that Australian Security Intelligence Organisation (ASIO) and other security forces should get access to private internet communications. A day or so later, Labor MP Anthony Byrne cited the London killing as a reason for ASIO’s bloated budget to be quarantined from the otherwise widespread funding cuts.

Rigbys’ death was undoubtedly terrible. Yet what made the stabbing of one man in a nation thousands of kilometres away sufficiently important to influence political priorities on another continent?

Though it’s impolite to say so, fatalities from terrorism remain vanishingly rare, at least in wealthy nations. You have four times the chance of being struck by lightning as you do from being killed by a terror attack. You are nine times more likely to choke to death on your own vomit; you are eight times more likely to die at the hands of a police officer than a terrorist. You are also something like a thousand times more likely to lose your life in a car crash than from a terror plot. Traffic accidents constitute a genuine threat; we all know someone who has died on the roads. Yet no-one would consider giving traffic officers anything like the powers accorded to security agencies, even though a far more intrusive policing of drunk driving would, without question, save hundreds of lives.

So let’s return to Woolwich.

“The attack was unprecedented”, noted Nick Miller in a widely syndicated Sydney Morning Herald piece, “[T]his has been security chiefs' greatest fear, an attack straight from the playbook of the new, ‘lone-wolf'’ brand of terrorism.”

Unprecedented? New? You can describe a knife attack in many ways, but novelty is not among them. Julius Caesar died in 44 BC from the blades of conspirators, without Brutus needing to consult this mysterious “playbook” (and, in passing, let’s also note the idiocy of the phrase “lone wolf” used to refer to, um, two assailants). As for the stabbing of an off-duty soldier embodying “the greatest fear”, well, the whole notion illustrates how divorced from reality such discussions have become.

In 2001, the US Department of Homeland Security issued a bulletin warning that Al-Qaida had, as its top priority, the detonation of a so-called “dirty bomb” (a radiological weapon) somewhere in America. A few years later, Condoleezza Rice urged an invasion of Iraq on the basis of an amalgam between Saddam Hussein, terrorism and nuclear weapons (“we don’t want the smoking gun to be a mushroom cloud”).

In other words, back then, security experts justified the huge escalation of their budgets and the implementation of unprecedented anti-terror laws on the basis of the destruction of entire cities. But in 2013, we should apparently be as scared of machetes as of nuclear bombs.

“There is a particular horror associated with low-grade or homemade violence of this kind …” explains the New Yorker. “[T]here remains something hideous about the use of weapons that are, to other people, barely weapons at all, but household or kitchen implements.”

A particular horror associated with … kitchen implements? With such arguments, we move from security into theology, a realm in which whatever weapons terrorists employ become the Worst Weapons of All.

Something similar became apparent during the discussions about the closure of Guantanamo Bay. In the course of that unedifying debate, we learned that terror suspects could not be tried on US soil, nor detained in high-security prisons. Why not? The US legal system that processed all kinds of murderers and psychopaths could not, apparently, cope with those accused of terrorism, whose existential evil was such that it would somehow magically leak out from a supermax gaol.

Hence the comparison with witches. The point’s not that terrorism doesn’t exist, for clearly it does. It’s that we discuss terror in the same fashion that the Maleficarum discusses witchcraft, as a phenomenon that cannot be assessed by its actual consequences.

It wasn’t always thus.

Amazingly, between 1968 and 1973, terrorist incidents involving the seizure of commercial jets took place at a rate of nearly one a week, a sequence of skyjackings now almost totally forgotten. The attacks were taken seriously, of course – but no-one suggested they posed an existential threat, nor claimed world had somehow changed forever.

Now, ask yourself this: what would be the reaction today to a similar spate of terror attacks? If two men wielding a machete on an entirely different continent spurs calls for increased surveillance of your emails, how would Greg Sheridan and his ilk react to five years of weekly skyjackings? What kind of security state would they demand in response?

The comparison between the political culture then and now helps explain the rise of the theological response to terror. In the politicised climate of the late 1960s, skyjackings were understood in a particular context. Even those with no sympathy for the militants’ aims accepted that the perpetrators possessed a motivation for their crimes, that they were not simply driven by a fathomless evil.

Today, however, the mainstream response to terrorism deliberately strips acts from context. In his piece on Woolwich, Sheridan berates what he calls “absolute nonsense of blaming terrorism on US, British or Australian foreign policy” – even though the accused men repeatedly citing Western attacks on Muslim countries to justify their crimes.

With discussions of the rationale for terrorism explicitly excluded from the public realm, it’s no wonder we return to the logic of the Maleficarum, where deeds matter most not in and of themselves, but because they manifest a theological evil. From that perspective, it’s impossible to over-react to terrorism: two men with knives indeed pose a threat equivalent to a nuclear bomber, since the real menace comes from their souls rather than their weapons.

Of course, as the witch hunters of old knew, campaigns against a spiritual evil provide rich opportunities for those able to keep the populace sufficiently terrified. All over the western world, our contemporary Hammers of the Terrorists have done very nicely out of the security state, and they’re unlikely to cease any time soon.

• Comments on this piece will be turned off for legal reasons