I was surprised to learn that in Northern Ireland, you are legally required to ask candidates whether they are Catholic or Protestant. If they decline answering, you must make an educated guess and document that. The goal is to ensure you are not hiring all Catholics or all Protestants.
Northern Ireland is in a unique situation. The Troubles were horrible. I can’t imagine having to write regulations to put a society back together. I should not judge the wisdom of this approach. It is just so different from what I am used to in the U.S., that it is hard not to be confounded.