I'm going to add a second, more substantive Answer:
So, googling indicates that QueerTown is an Australian entity - so Australian law is the benchmark here.
The Fair Work Act states that it is unlawful for employers to discriminate against an employee based on religion. Religious discrimination refers to any adverse action taken against an employee because of his/her religion, and can include not hiring someone, treating an employee less favorably than other employees, or terminating an employment contract.
(from: Here)
Now - from my understanding, there is not Blanket protections things such as:
- Observance of the Sabbath
- Wearing certain clothing that interferes with Safety etc.
Is not protected.
The litmus test is whether or not the religious observance would impact your ability to do your job.
In most scenarios, I think you would have a very good case to refuse on religious grounds. Where you might have trouble would be if the position was one where it would be reasonable that you would regularly and specifically interact with AlphabetLGBTQ+ people as part of your job - so for example, if you worked as a counsellor.
I think it would be more interesting to argue that the institution is advancing a political agenda and that requiring you to attend would be discriminatory on that grounds. There have been some cases recently in UK law that would be interesting (and yes, the Australian legal system does regularly look at cases in the UK and NZ for reference where there are similar questions being asked.
In short - Your employer would have a hard time justifying that such a workshop is required for you to do your job, as such you can refuse it. If you face backlash, a well worded legal letter from a lawyer that you believe you are facing discrimination at work due to your religious beliefs should either cut it out or provide grounds for lawsuit further down the line.