The belief that people can’t change their sex is “absolutist” and “incompatible with human dignity and fundamental rights of others”.

That is the ruling just made by a UK employment tribunal judge in the case of a woman denied work over “offensive” tweets. The judge also declared “not worthy of respect in a democratic society” the belief that a person born male is not (and cannot become) a woman.

And, incredibly, lack of belief in gender understood as identity does not give protection from discrimination under the Equality Act 2010. The judgment is bad news for the claimant, Maya Forstater, and more broadly for people everywhere who are sceptical of the new gender ideology.

Across several countries, a war over words is raging: what is a woman? This question led to angry protests at the University of Melbourne this year when the Victorian Women’s Guild hosted an event to discuss Victorian legislation proposing to make “wom­an” a category anyone can identify into, by making legal sex a matter of mere statutory declaration. Those opposing the bill argued it undermined women’s spaces and services, while those supporting the bill hailed it as a progressive step in the fight for trans rights. The bill passed and comes into effect by May next year. In Victoria, a woman will be anyone who declares themselves one.

Similar legislation has been proposed in New Zealand and the UK, leading to vociferous debate over the meanings of female and woman and the concepts of sex and/or gender they refer to.

Women are fighting not only against legislation that fundamentally changes what it means to be a woman (from a biological fact to an identity category) but against surreal attempts at policing their political and philosophical beliefs about womanhood and feminism.

Women expressing what have come to be known as “gender-critical” beliefs – chief among them the belief that a woman is an adult human female – are now routinely subject to social media pile-ons, letters of complaint to employers, the posting online of private details to expose them to more harassment, and worse. For “misgendering” (using sexed pronouns for a trans person), “deadnaming” (referring to a trans person by their former name), and using allegedly offensive terms, women in the UK have been subject to police interview or investigation. Twitter bans the accounts of women who use the wrong pronouns for trans people. But the gender wars had yet to be fought in a courtroom. This changed with the crowd-funded Forstater case.

Forstater’s beliefs about what a woman is brought her into conflict with her employer and led to her not being offered another contract with the London-based Centre for Global Development. She was working for the centre during the period of public consultation over changes to the Gender Recognition Act 2004 and tweeted openly about her opposition to it.

The GRA awards applicants with a Gender Recognition Certificate, effectively changing their legal sex. Successful applications currently require a diagnosis of gender dysphoria (or discomfort with one’s body), and evidence of having lived in the “acquired gender” for at least two years. The proposal was to change this to a single-step statutory declaration or “self-identification”. This div­orces the concept of sex from a physiological reality and turns it into an identity. This is the change made in Tasmania and Victoria; British women were able to mobilise a more effective resistance.

Forstater opposed the reforms to the GRA on the grounds that it is impossible to change sex, that sex is politically important and should not be conflated with gender identity, and that the reforms would be likely to undermine the provision of women-only spaces, services, and protections by making them de facto mixed-sex. She said in her live evidence that she did not consider a Gender Recognition Certificate to make a significant difference to the importance of sex classification. In her witness statement, she wrote that “avoiding upsetting males is not a reason to compromise women’s safety, dignity and ability to control their own boundaries as to who gets to see and touch their bodies”.

The judge’s decision hinged on the balance between freedom of expression and protection of belief, on the one hand, and protection of rights and dignity, on the other. He granted that Forstater’s understanding of sex and gender, and her conception of a woman, counted as a “philosophical belief” on four out of five of the “Grain­ger” criteria established by a 2010 case of that name. These are that the belief is genuinely held; is a belief rather than an opinion or viewpoint; is about a weighty or substantial aspect of human life; and attains a level of seriousness and importance.

But he denied the belief met the fifth criterion, namely “it must be worthy of respect in a democratic society, not be incompatible with human dignity and not conflict with the human rights of others”. Forstater’s beliefs were found to be incompatible with the human dignity and fundamental rights of others (implicitly, of transwomen). Thus her beliefs ultim­ately do not count as a philosophical belief and are not protected by the Equality Act 2010.

The implications of this case in the UK are that women may be fired for expressing gender-critical beliefs. Forstater’s claim was that her employer had engaged in direct discrimination on the basis of her philosophical beliefs, and indirect discrimination on the basis of sex (women are more likely to hold gender-critical views). The judge found against her, which means there is now a precedent for this kind of discrimination.

In the UK, where there is still some gatekeeping around legal change of sex, this leaves room for the expression of scepticism about the status of merely self-declared transwomen as being women. But were judges in Victoria or Tasmania to follow suit, the implications could be totalitarian indeed, given that legal change of sex in those states is possible on the basis of declaration alone. Do we really want to live in a society in which women can be fired from their jobs for denying that a 6 foot 2 inch bearded male is a woman?