The idea
Of all of the employment discrimination legislation the protection of religious beleif is the only one that is about choice. Employees (or potential employees) are not able to choose their gender. age, race, sexual orientation etc and as such thses pieces of legislation are necessary. People choose their religious belief and, as such, should accept that all choice brings consequences.
This does not mean that I advocate any form of bullying, harrasment or other nasty things towards people who hold particular beliefs – this would all remain covered by other laws anyway. However, I do think we should have the right to consider a person's beliefs (if relevant) when making recruitment and career decisions about them.
Why is it important?
Religious belief is used far too often to hide behind in the workplace. It can paralyse employers from making sensible business-driven decisions due to fear or high cost.