I, for one, am not mourning the death of Martin McGuinness, the former deputy first minister of Northern Ireland.

Sure, in the last two decades of his life the leader of the essentially Catholic Sinn Fein party played an important role in implementing the 1998 Good Friday peace agreement in co-operation with Ian Paisley and other key figures in the essentially Protestant Democratic Unionist Party.

It’s just that McGuinness was an operative in the Provincial Irish Republican Army (or Provos) which in the 1960s, 70s and 80s waged terrorist war on Britain and those who favoured Northern Ireland remaining part of Britain.

Moreover, in Northern Ireland the Provos implemented a wave of terror within their own Catholic community, striking against alleged traitors and the like, even to the extent of murdering mothers of young children.

During their visits to Australia I received invitations to meet McGuinness and Sinn Fein supremo Gerry Adams (who has claimed not to have been a member of the Provisional IRA).

But I declined the opportunity since I have always supported a peaceful, constitutional and democratic outcome to Britain’s Irish question.

For all the blood that McGuinness and fellow comrades had on their hands, at least his goal was potentially achievable. Put simply, the Provisional IRA wanted Britain out of Northern Ireland and sought to establish a left-wing authoritarian regime over the land.

In the end, the Provos failed to achieve their immediate aim because the leadership aged and the cause was diminished by the growing prosperity of Ireland. Not enough young men wanted to follow in the footsteps of McGuinness and Adams. The Provisional IRA has not gone away but it is not the terrorist organisation it once was.

However, as this week’s terrorist attack on Westminster demonstrated once again, Britain remains under attack, this time by militant Islamists of various hue — al-Qa’ida, the so-called Islamic State or Daesh, and miscellaneous individuals who are classified as lone wolves.

The Provisional IRA wanted autonomy for all of Ireland. In Spain, ETA wanted self-government of the Basque area. And in the late 60s and 70s leftist terrorist organisations such as the Weather Underground and the Symbionese Liberation Army demanded change in the foreign and defence policies of the US.

Whatever their composition, all these organisations had essentially secular aims. Not so those who identify as radical Islamists. They see themselves as acting in accordance with what they regard as the wishes of the Prophet Mohammed and implementing what they interpret as the teachings of the Koran along with the requirements of Islamic law.

The Islamists of various kinds who have led attacks in the past two decades in New York, Washington, Madrid, London, Paris, Berlin, Nice, Brussels, Sydney and more besides demand the destruction of Western democratic societies and their replacement by an Islamic caliphate that will govern in accordance with sharia law.

In other words, the Islamists who attack the West have demands that are inconsistent with the existence of Western societies. In short, their demands are non-negotiable. Moreover, many believe salvation can be gained by what they term martyrdom.

Apologists for Islamists in the West like to compare jihadists to what they depict as the Catholic Provisional IRA. But the Irish Republican Army — under its various names — was a secular organisation with secular aims.

That’s one reason the Catholic Church in Ireland, and elsewhere, constantly condemned the IRA’s acts of violence. Likewise, the Protestant extremists, with whom the Provos fought, also had a secular aim: the maintenance of British rule in Belfast. Neither side saw itself as fighting for God but, rather, for their concept of country.

It’s true that the overwhelming majority of Muslims living in Western nations support the continuation of Western democratic secular societies. But it’s also true that a very small but strong minority of Muslims living voluntarily in the West do not accept Western society. It is from this group that the Islamist terrorists come.

Of particular concern is the fact some jihadists, unlike most terrorists, are willing to take part in suicide attacks. This means deton­ating bombs that result in instant death or taking part in the kind of sole attacks seen recently in Nice, Berlin and now London, where a terrorist knows that they will be killed at the hands of security or police forces but goes ahead with the attack.

At the moment, the jihadists in our midst have knives, pistols, firearms, bombs and cars/trucks. But it’s not impossible that they could soon have some kind of chemical weapons and even dirty nuclear material.

In the wake of the Boston Marathon bombings, Monash University academic Waleed Aly (who has been promoted by the ABC, Fairfax Media and Network Ten’s The Project) described the murders by the Tsarnaev brothers as demonstrating that terrorism is a mere “perpetual irritant”.

A germ warfare or dirty nuclear attack on London could do more long-term damage than that achieved by German bombers during World War II. Viewed in this light, terrorism is no irritant — perpetual or otherwise. It could result in the full or partial evacuation of large cities.

There is more freedom for Muslims (Sunni or Shia alike) to practise their faith in the West than in other parts of the world. Most Muslims who have chosen to live in the West recognise this. But a minority do not.

London-born commentator Trevor Phillips, who is of Guyanese background, referred in London’s The Sunday Times (April 10, 2016) to a chasm opening up between the majority of Muslims who are satisfied with British society and the small minority who are seriously alienated.

Phillips proposed a “far more muscular approach to integration” by British authorities with respect to ethnic groups. The recent ­attacks on the centres of Western democracies demonstrate the ­urgency of such a task. Viewed in this light, assistant minister Zed Seselja’s release last Monday of the Coalition government’s Multicultural Australia: United, Strong and Successful statement — with its emphasis on the unifying effect of all Australians speaking the ­English language — is a step in the right direction.