Just when you thought society was safe from metaphors of the military kind, the Australian Sex Party has declared war on the Catholic Church.

The pronouncement was made by Victorian parliamentarian Fiona Patten, who is also ASP president, in an email to her supporters on Tuesday.

Last week the Prime Minister and his Treasurer were criticised by sections of the media for suggesting the Labor Party had “waged war” on business. But there has been scant reaction to Patten’s call for “all-out war on the Catholic Church”.

This follows the report in the Guardian Australia on Saturday that two nuns from Mother Teresa’s Missionaries of Charity had defaced a Sex Party poster in the inner-city Melbourne suburb of Collingwood that called on voters to “Tax the Church”.

You would think the online free newspaper had more important issues to cover than the actions of two nuns, apparently of Indian descent, scratching out the “Vote Sex Party” at the bottom of the sign. Apparently not.

For the record, the nuns did not deface the Sex Party’s “Legalise cannabis” poster. Perhaps they were disturbed by the ASP’S depiction of a dollar sign on a crucifix that accompanied the tax exhortation.

Fair enough. If a dollar sign were imposed on a depiction of the Prophet Mohammed or the Koran it is likely Gillian Triggs and her professional offence-takers at the Australian Human Rights Commission would be calling for action.

The concern of Indian-born nuns appears to be of lesser moment to the HRC and like bodies.

Patten’s aim is to raise $25,000 for a video in which she will “talk about key issues like marriage equality, voluntary assisted dying and ending tax exemptions for religious organisations”. These are legitimate issues to address, from the ASP’s point of view.

However, what is of concern is Patten’s virulent anti-Catholic sectarianism, which resembles that which prevailed during and after World War I. Her email contains the following comment: “Whether the Liberals or Labor win the election, we still end up with a Catholic prime minister.”

This statement is false. Malcolm Turnbull was educated at the non-denominational Sydney Grammar School and became a Catholic when an adult. Bill Shorten was baptised a Catholic and finished his schooling at Xavier College in Melbourne, a Jesuit school.

However, on marrying his second wife, Shorten converted to Anglicanism. Contrary to Patten’s claim, Shorten is not a Catholic.

But what if he were? On the ABC’s 7.30 on Wednesday, Turnbull told Leigh Sales he supported same-sex marriage and he “will certainly be voting yes in the plebiscite” on the issue.

The Opposition Leader also supports same-sex marriage but believes the issue should be legalised by parliamentarians without a plebiscite.

Patten seems to hold the view of anti-Catholic sectarians of old that all Catholics do what the popes and bishops tell them to do with respect to faith and morals. This is ignorant nonsense.

It is true that the Catholic Church holds the traditional view that marriage is a union between man and woman. However, this is not an exclusive Catholic position. It is also held by many other Christians, Buddhists, Hindus, Jews, Muslims and quite a few agnostics and atheists.

After all, this was the accepted view of marriage up to about a decade ago. The 2004 edition of Butterworths Legal Dictionary defines marriage as “the union of a man and a woman to the exclusion of all others, voluntarily entered into for life”.

It should not surprise the ASP that, in a socially conservative nation such as Australia, there is resistance to proposals for sudden change of the marriage act. But Patten is delusional if she focuses on the resistance to same-sex marriage by the Catholic Church.

It’s much the same with euthanasia. Sure, the Catholic Church opposes the deliberate ending of life, even though not all Catholics support the church’s thinking on this matter. But this is not a position taken by all Catholics.

On ABC TV’s The Drum on May 25, former disability discrimination commissioner Graeme Innes said he did not believe “we have the right to take another life”. He expressed the reasonable concern that “it’s a small step to talk about people who are terminally ill” to then go and “talk about people with disabilities” as candidates for euthanasia.

This is an essentially secular, and pragmatic, position.

The ASP also wants to end tax exemptions for religious organisations but not, apparently, for secular not-for-profit organisations. Patten wants to tax the Catholic Church but not the Rationalist Society or the trade union movement.

On Tuesday, the Sydney Institute hosted a discussion between Ross Fitzgerald (the ASP’s lead candidate for the Senate in NSW) and Fred Nile (president of the Christian Democratic Party).

Both parties are contesting the Senate election in every state. Before an engaged but polite audience, Fitzgerald spoke on several occasions about the ASP’s commitment to tax religious organisations. Nile responded that the Christian churches would be prepared to pay tax if the state compensated them for all the educational, welfare and health services they had provided for free, saving taxpayers massive amounts of money. Mary MacKillop (1842-1909) is perhaps Australia’s best known Christian. She established a Catholic order of nuns, the Josephites, which devoted itself to educating the poorest of the poor. MacKillop also ministered to poor women who were driven into prostitution because of their economic circumstances.

Secular organisations such as the Fabians or the ­Rationalists did no such comparable work.

There is also another double standard here. Patten has taken a position in support of her party’s “Tax the Church” posters. Yet, so far, no one in the ASP has put up a “Tax the Mosque” poster in, say, Lakemba in Sydney or Coburg in Melbourne.

It seems that Patten and friends do not want a war on more than one front.