Dr David Mackereth told a panel that using transgender pronouns was "a ritual denial of an obvious truth".
The 56-year-old from Dudley, claims the Department for Work and Pensions (DWP) discriminated against his religion by suspending him after he said he would not use gender pronouns for what he called someone's "chosen" sex.
The "unashamedly Christian" doctor has taken the government to an employment tribunal after he was allegedly dismissed weeks after starting as a Universal Credit assessor following a dispute with a manager at a Birmingham centre in June 2018.
The DWP maintains that his stance would be "unwanted conduct" towards those undergoing gender reassignment and could have constituted harassment under the Equality Act.
But Dr Mackereth's lawyers, supported by the Christian Legal Centre, are putting forward the case that the DWP's policy of forcing staff to use "gender pronouns" is a breach of equality legislation and denies the doctor freedom of thought.
The former emergency department doctor of 26 years argued that maleness and femaleness are “unchangeable and fundamental to who we are as people who were created in the image of God”.
On the opening day of the tribunal, during which he repeatedly read passages from the Bible, Dr Mackereth denied that his views were offensive.
He called the DWP's decision to allegedly sack him "sinister".
Recalling an incident that allegedly lead to his dismissal, the devout Reformed Baptist told the tribunal that an “argument arose” with his manager not over “rights and sensitivities” but instead “my refusal to make an abstract ideological pledge to call any six-feet tall bearded man 'madam' on his whim.”
He added: “Throughout this process I kept stressing that my objection to that misuse of pronouns was based on my Christian beliefs and conscience.”
Dr Mackereth, claims that weeks after applying for the post in May 2018 and while on a two week training course, he was called aside by James Owen, the recruitment manager who had interviewed him weeks earlier, and questioned.
"I was engaged in working on my second real case when Mr Owen called me out of my work," he said. The purpose was to interrogate me about my beliefs in relation to the use of pronouns.
“That discussion culminated in Mr Owen asking me the following question - 'Let's just summarise this. If you have a man six feet tall with a beard, who says he wants to be addressed as 'she' and 'Mrs' - would you do that?'
Dr Mackereth claims that after telling him he could not "in conscience" do this because of his religion, Mr Owen said that failing to use transgender pronouns meant her was at overwhelming risk of losing his job.
The DWP denies Dr Mackereth's beliefs are “protected” under the Equality Act, while the recruitment agency which appointed him to his post has argued that his views conflict with the fundamental rights of others.
Dr Mackereth has insisted that no effort was made to accommodate his beliefs, such as referring transgender clients to other staff.
He claimed not to be aware of any training documents requiring use of pronouns "in accordance with arbitrary choices rather than in accordance with English grammar and common sense."
At the conclusion of his opening statement to the tribunal panel, Dr Mackereth said: "The very fact a doctor can be pulled off the shop floor for an urgent interrogation about his beliefs on gender fluidity is both absurd and very sinister."
Asked if he thought such views would undermine the dignity of a patient, he replied: "I believe that we are made in God's image - male and female," he told the three-member tribunal panel. I do not believe that it would undermine somebody's dignity."
He added: "I don't believe a person can change their gender. It's not scientifically or medically possible. We have a problem here of two world views that struggle to accept each other."
Robert Moretto, representing the DWP, asked Dr Mackereth about the General Medical Council code of conduct, which states you must be “polite and considerate” to those being assessed and not express personal beliefs to patients which may cause distress.
Dr Mackereth said of the regulations: “It doesn't stop me from saying: 'I am sorry, I am Christian, there are some things I can't do.' I can't be forced to do something that goes against my conscience.
"What I am saying about pronouns is not going to affect the quality of the assessment that I do. I don't object to doing assessments on transgender people.”
The tribunal continues, and comes after a poll last week which found that more than half of Britons support the right for transgender people to self-identify.
The results, from a survey of 1,720 adults, have raised hopes among campaigners that the Gender Recognition Act will be reformed to include this stipulation.
Currently the issue of gender pronouns is covered with ambiguity in the Equality Act, but some sectors from higher education to healthcare have placed into internal policy the rule that "misgendering" an individual is discriminatory.
In April school pupils in Brighton were urged to wear "pronoun stickers" to avoid transgender children being referred to in a way that makes them feel uncomfortable, a measure also implemented by Edinburgh University during freshers week last year.
Gender pronouns range from "he" and "she" to more nuanced forms such as "xie" and "ey".
Agencies contributed to this report
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