When Ephialtes of Trachus betrayed the Spartans at Thermopylae (you remember the grotesque hunchback from The 300) his mind doubtless was on the reward he expected to receive from Persian King Xerxes. He never imagined his greed-induced act of perfidy would generate an infamy that would endure through the ages.

But so reviled is Ephialtes in Greek national memory that even today his name is a by-word for traitor. Like Judas Iscariot in Christianity, Vidkun Quisling in Norway or Benedict Arnold in America, he is such a figure of contempt that the name Ephialtes has become a metonym for turncoat in modern Athens.

After the display of Turnbull-esque knavery at the Wentworth by-election, I might be inclined to add Malcolm to this pantheon of treachery. But in order to break faith with something, a person must first have faith to break. And it’s clear as a sunny summer’s day that Turnbull was never a genuine adherent to the Liberal creed. How can we know this? We can start with the story told by retired ALP Senator Graham Richardson how Turnbull ‘begged to be placed on the Labor Senate ticket’ during the mid-1990s. Add to that Turnbull’s enduring fervour for green-tinted policies that would gladden the heart of any dreadlocked tree-hugging enviro activist.

Never mind that Turnbull’s devotion to Labor’s emissions trading scheme cost him the Liberal leadership in December 2009. When he reclaimed the prime minister’s suite six years later, Turnbull took another bite at the poisoned apple by seeking to coerce power companies into abandoning low-cost coal in favour of higher-cost renewables.

Turnbull’s fraught relationship with environmental policy brings to mind Winston Churchill’s quip about second marriages: ‘the triumph of hope over experience.’ But his unremitting effort to impose left-wing climate change policy on a centre-right party was hardly his sole march of folly. In 2017, Turnbull proudly announced that his new Gonski 2.0 education policy would ‘bring the school funding wars to an end’. Yet the inherent flaws in the Gonski formula so enraged the Catholic school sector that they ignited a political conflagration that seriously singed the Turnbull government.

Here was a Coalition prime minister picking a fight with an education-sector stakeholder that operates 1,700 schools scattered across every federal electorate in Australia. Never mind that the Catholic community had proved to be a reliable base of electoral support for the Liberal party since the ALP split of the 1950s.

Last December’s ministerial reshuffle provided a perfect opportunity to dampen those flames by shunting Simon Birmingham to a less toxic portfolio. But in a no-move move that befuddled most political observers, Turnbull chose instead to stand by his man in firm Tammy Wynette fashion. Birmingham was left in place to stoke the embers of Catholic resentment until the demise of the Turnbull government last August.

Of course, the stoush with the Catholics was not the only cause of Malcolm Turnbull’s political destruction. But there’s no doubt this entirely unnecessary school funding fight became a suppurating sore that festered amongst Coalition backbenchers fearful of their own political survival.

These two episodes of self-inflicted political injury – climate change policy and school funding – illustrate another pernicious facet of Malcolm Turnbull’s character. After rushing in where even fools should fear to tread, he shamelessly tucked tail and slunk away from these messes of his own creation. When push came to shove, the only interest Malcolm Turnbull really cared about was his own.

After losing the Liberal leadership in December 2009, Turnbull completely spat the dummy. He wrote a petulant opinion piece in Fairfax that could have been copied verbatim from the Greenpeace songbook, describing Tony Abbott’s climate change policy as ‘bullshit’.

Sound familiar? But rather than pulling the pin and galivanting off on holiday to New York back in December 2009, Turnbull was talked off the political ledge by none other than John Howard. I would be very surprised if, in retrospect, Howard doesn’t regard this as one of the greatest errors of his political life.

From start to finish the Turnbull experience has been an unmitigated disaster for the Liberal party. But the political perfidy of Ephialtes of Wentworth is merely a symptom of a far more insidious disease.

Liberals like to describe themselves as a broad tent that encompasses both ‘classical liberal’ (read libertarian) and conservative strains of political philosophy. And when Menzies first established the party in 1944 the gap between those two schools of thought was a mere rivulet that, like Frank Lloyd Wright’s famous ‘Fallingwater’, could comfortably flow within a single edifice.

But now, 84 years later, those differences have widened into a veritable Grand Canyon. The simple fact is that soi disant Liberal ‘moderates’ like Trent Zimmerman and Simon Birmingham have more in common with the Greens on matters of faith and family than with conservatives like Andrew Hastie and Eric Abetz.

These tectonic shifts in Australia’s social landscape have generated political pressures that are causing the broad tent to buckle. The resulting clash of contending worldviews has produced centrifugal dynamic that has emptied the Liberal party of any coherent ideological value system. And as we’ve witnessed, values matter because in their absence governments end up wielding power for power’s sake rather than as a means to an end.

Sir Robert Menzies warned of this cognitive rot over 40 years ago in an oft-quoted letter to his daughter. But I doubt even he could envisage a nightmare scenario in which a man who had once begged for ALP preselection could rise to preside over the Liberal party as PM.

Malcolm Turnbull’s tenure at the apex of Australian politics is a testament how far the moral termites have spread within the Liberal party and how truly well they have dined. At some future point – and I suspect sooner than many might think – the canvas of that tent will rip to reveal the gaping values chasm within. The secession of Cory Bernardi was merely the initial manifestation of a schismatic energy that will soon tear the Liberal party asunder. It can’t come too soon for me.