It’s possible Education Minister Simon Birmingham may have missed some Bible classes when growing up in South Australia in the 1970s and 80s. How else to explain his claim on Sky News that the Catholic Education Office in Victoria had been bought by Bill Shorten for a “few pieces of silver”?

As readers of the New Testament will be aware, Judas Iscariot was an apostle of Jesus Christ who betrayed Jesus’ identity to the Roman authorities for 30 pieces of silver. It’s true that the Catholic Education Office supported Labor candidate Ged Kearney in the Batman by-election in Melbourne last Saturday. It did so following the Opposition Leader’s promise that, if elected, Labor would provide an extra $250 million to Catholic schools during the first two years of government. But this was no Judas-style betrayal.

For starters, the Liberal Party did not contest Batman. The contest was between Labor’s Kearney and the Greens’ Alex Bhathal. In the 2016 election, the Liberal Party preferenced Labor’s David Feeney ahead of Bhathal. So it should be assumed that the Liberals would prefer to have Labor holding Batman than the Greens.

In any event, neither the Catholic Church nor its various institutions has ever been an “apostle” or member of the Liberal Party. Over the decades, Catholics have voted for major and minor parties except, presumably, the Communist Party many decades ago.

It’s understandable Birmingham is disappointed about being criticised over commonwealth funding for Catholic schools. It’s natural to expect that he would be none too pleased with the Victorian Catholic Education Office’s support for Shorten on this issue. But, again, no betrayal is involved.

Birmingham’s comment on Sky News that “there’s always somebody who can be bought by a few pieces of silver” also overlooks the fact most governments, institutions and individuals want more. Including South Australians, like Birmingham, who want their state to receive more defence contracts from the commonwealth. It’s called politics.

There is a lot of political history in this issue. Only four Liberal leaders have won office after defeating Labor at an election: Robert Menzies (1949), Malcolm Fraser (1975), John Howard (1996) and Tony Abbott (2013). Fraser, Howard and Abbott understood the importance of attaining and maintaining the support for the Coalition from Catholics, many of whose children are educated in the Catholic education system.

And then there is Menzies. In his early years in office after ­December 1949, Menzies adapted to what was a bipartisan policy at the time — namely, that there should be no state aid for non-government schools. Until around the middle of the 20th century, most Catholics had voted Labor. But this changed in the mid-1950s following the Labor Split, which had a large impact in Victoria and Queensland but affected all states.

The Democratic Labor Party, which was formed after the Split by those who were expelled from the ALP, preferenced the ­Coalition ahead of Labor throughout Australia. This saved the Menzies government in December 1961, as it would save John Gorton’s government eight years later.

Menzies was shocked by his near defeat in 1961. In the lead-up to the (early) 1963 election, the ­Coalition promised to provide commonwealth funding for science blocks in government and non-government schools. This was the first breakthrough in the Catholic Church’s long campaign for what was called state aid.

The breakthrough at the state level came in 1967 when Henry Bolte’s Liberal government promised that, if re-elected, it would give per capita grants to students in non-government primary schools.

Again, the change agent was the DLP, acting with BA Santamaria’s National Civic Council. The DLP threatened to preference against Bolte’s candidates in favour of the Country Party, not in coalition with the Liberals at the time. Bolte was not threatened by Labor in 1967 in Victoria. But he was worried his government could lose seats in rural Victoria. Hence the per capita grants to shore up DLP preferences. The deal was a win for the Catholic Church and a win for Bolte.

It is part of Australian mythology that the so-called “Goulburn school strike” in July 1962 was the breakthrough that ended the state aid debate. In fact, while the incident attained considerable publicity as Catholic parents moved their children to government schools in the diocese of Goulburn, it did not achieve a significant policy breakthrough. The students went back to their Catholic schools after a short period.

The likes of Menzies (from 1963), Fraser, Howard and Abbott and their state equivalents all understood that the Catholic low-fee systemic school system took pressure off the government school system. And they recognised the importance of Catholic support for the Coalition.

One of the problems of the Liberal Party today is that it underestimates the political skills of Shorten. Labor’s pitch in Batman to Australians who send their children to low-fee Catholic schools (many of whom these days are not Catholic) was clever politics. What’s more, it comes at the cost to the budget of $250m over two years, which is not a huge ­expense.

It’s not only the Catholic Church in Victoria that is concerned about funding from the Turnbull government following the implementation of the Gonski reforms. As Simon Benson reported in The Australian on Thursday, two-thirds of Catholic schools in the diocese in Broken Bay (which covers Sydney’s north shore and northern beaches along with the Broken Bay and central coast regions) have recorded declines in enrolments after fee increases.

The fee hikes followed the Turnbull government’s reduction in funding to many low-fee Catholic schools. Similar concerns have been expressed in the ACT, South Australia and elsewhere.

Trailing in the opinion polls, the last thing the Turnbull government needs to do is to alienate its supporter base. But that is what it appears to be doing right now, contrary to the political lessons left by Menzies, Fraser and Howard.