It is unlawful to refuse you promotion because of your religion or belief. The only exception to this protection is where there is some reason connected with the job itself, or the nature of the job requires a person of a particular religion or belief. This is known as a Genuine Occupational Requirement (GOR).
However, GORs are narrowly interpreted. Your employer can only refuse to promote you because of your religion if the nature of your role requires you to hold a particular religious belief or levels of religious knowledge and/or commitment. An example might be where you are applying for promotion to a leadership role in an organisation that had a strong religious ethos.
When inviting candidates to apply for the promotion, your employer should have spelled out clearly that the successful candidate needed to demonstrate a particular religious belief. There is guidance on this in the Equality and Human Rights Commission Statutory Code of Practice (PDF).
If you suspect you have been turned down for promotion because of your religious beliefs (or lack of belief), there are a few preliminary steps you can take. For example, you can write to the organisation, explaining your suspicions and asking for an explanation as to the basis for their decision, following guidance on asking questions about suspected discrimination provided by Acas (PDF).
You may decide to bring an employment tribunal claim. The deadline for bringing such claims is very short – just three months from the date of the discriminatory act – and strictly enforced.
You can find more information about bringing a claim in our Enforcing your rights section.