Can an employer restrict a job to people of a particular religion or belief?

A job can be restricted to candidates of a particular religion or belief only where, having regard to the nature of the employment or the context in which it is carried out, being of that religion or belief is a genuine and determining occupational requirement for the job and it is proportionate to apply that requirement in the particular case. If the employer is an organisation with an ethos based on religion or belief, it will be enough that being of the particular religion or belief is a genuine occupational requirement (ie it does not have to be a determining requirement) and it is proportionate to apply that requirement in the particular case.