I'm pretty sure that current employment law prohibits discrimination against people because of factors such as creed\race etc. So why is this youth centre allowed to say they seek to hire committed Christians and require a reference backing this up (example: from a priest)?
http://www.salmoncentre.co.uk/vacancies.htm
http://www.salmoncentre.co.uk/docs/Application Form.doc
http://www.salmoncentre.co.uk/vacancies.htm
http://www.salmoncentre.co.uk/docs/Application Form.doc