@HebrideanHecate @Gnomeshatecheese People in any profession can hold any beliefs they want and express them too.
But if a person's beliefs come into conflict with the work they must do then they may be in the wrong profession. Why apply for a job you think is morally wrong or for which you are ill-suited?
If the ethos and practices of the profession change drastically during the person's working life, then it might be important to speak up to draw attention to it. But if a person cannot continue to work there in good conscience, then they should resign.

Thinking about this, what might the cases of the Darlington nurses and Sandie Peggie look like if they had made a high-profile case of resigning because not only had the ethos of providing single-sex changing spaces drastically changed in their work place, but that their union agreed with the drastic change? What if they had sparked a mass resignation of staff who also objected to the new policy?