In reviewing John Howard’s The Menzies Era in The Times Literary Supplementlast May, Clive James made a tough-minded assessment about refugees, immigration and all that.

James wrote: “Until recently, in Australia, every ethnic group that came in was assimilated if it wanted to: the Muslim extremists are the first consignment of immigrants to hate Western ­civilisation almost as much as the resident intellectuals do.” Tough minded, for sure. But fair. Except that the intelligentsia in Australia is not into murder and/or destruction.

On the other hand, some Islamists openly proclaim their intention to overthrow Australian democracy and establish a caliphate whereby everyone will live in accordance with the dictates of an Islamist theocracy.

Certainly this is the view of only a very small minority of the Muslim community. Yet it is both real and threatening. This was made clear in the important report by Sean Rubinsztein-Dunlop and Dylan Welch on the ABC’s 7.30 last Monday.

The program interviewed a 19-year-old supporter of the so-called Islamic State, or Daesh, who knew Farhad Jabar, the 15-year-old who murdered Curtis Cheng outside the Parramatta police station.

The 19-year-old, who came to Australia as a refugee from Afghanistan 10 years ago, did not attempt to disguise his hatred for Australia and non-Islamist Australians. While demanding anonymity on the ABC, the young man understands he is known to NSW Police, the Australian Federal Police and the Australian Security and Intelligence Service.

He described himself as “a normal dude”. But there was nothing normal about his religio-political ideology. Asked why he found it hard to say that Cheng’s murder was a tragedy for the victim and his family, the reply was brutal: “Why should I please the kafir — the ­disbelievers?”

So, to this Islamist, the battle is unambiguous.

There are Islamists like him and there are the kafirs. And he is waging war against disbelievers: “There is no other law except Allah’s law; people that smoke drugs, there’s no cigarettes, there’s no alcohol, there’s no brothels, there’s no clubbing — all shut down.” That’s life under the caliphate.

Earlier he had declared that “everyone wants to die for Allah” and those who died for Allah get to live “the best life in the hereafter”. It was no surprise, then, that he declined to answer whether he was prepared to get killed for Allah. This, after all, is the Islamists’ distorted interpretation of 15-year-old murderer Jabar’s death — who was shot by NSW police acting in self-defence.

The uncomfortable truth is that there are a number of Jabars in contemporary Australia who are prepared to kill kafirs, to die for what they believe is Allah’s cause. This deauthorises the position of academic Waleed Aly, who ­described such terrorist acts as the Boston Marathon bombing as a “perpetual irritant”, and journalist David Marr, who said last year that “the amount of fear being thrown into the community at the moment is disgraceful”.

The Islamists involved in acts of terrorism in Australia — or conspiracy to commit terrorism in Australia — during the past decade include Australian-born, immigrants and refugees alike. This problem is likely to be with us for a long time despite the best efforts of police and intelligence services along with the mainstream ­Muslim community.

In view of this reality, it makes sense for the rest of the Australian community to focus on what unites us rather than what divides. Yet this is not the fashion in Australia where, as James and others have noted, many of the best educa­ted happen to be the most alienated.

This is evident, for example, in the indigenous community. Talented actress Miranda Tapsell was interviewed by Karl Stefanovic on the Nine Network’s The ­Verdict on October 15. Despite her evident success, Tapsell said no when asked if she identified herself as Australian. Asked the reason for this, she replied: “When I go to Australia Day, I don’t feel like an Australian that day because people are telling me I can’t be part of that.” It is not clear who made such an assertion.

Asked whether she would sing the national anthem, Tapsell ­responded: “I’d mumble it in the corner of my mouth, maybe.”

Deborah Cheetham, associate dean of music at the University of Melbourne, has gone even further. In an article in The Conversation this week, the famous indigenous soprano revealed that she had declined an invitation to sing Advance Australia Fair at the Australian Football League grand final in Melbourne this month.

Shortly after her piece in The Conversation was published, Cheetham received a soft interview on ABC Radio 702’s program Mornings, hosted by Linda Mottram.

Mottram described the article as “wonderful” as the author spelled out her opposition to the words of the national anthem.

In short, Cheetham will not sing the words “For we are young and free” primarily because she believes it is condescending to indigenous Australians to describe the nation as “young”. Her point is that Aborigines, in what became known as Australia, go back more than 50,000 years.

True, of course. But it is also true that the Commonwealth of Australia was created in January 1901, which makes the country relatively young.

Moreover, many indigenous Australians have ­European, Asian or Islander ­ancestors in addition to their indigenous ancestors.

Tapsell, for example, told The Verdict that her father had an ­English and Irish background.

Mick Dodson in 2009 raised the familiar question as to whether Australia Day should be called “Invasion Day”. That was a reasonable point, provided that all Aborigines who have some ­non-indigenous ancestors acknow­ledge that they are part “invaded” and part “invaders”.

The threat to democratic ­society is real and immediate. It makes sense to embrace the reality of a young and free nation and to reject alienation, whether it is sparked by discontented intellectuals or murder-endorsing ­extremists.