I think I would rather treat people as individuals than as stereotypes, particularly as there is such a wide range among various groups. It’s too easy to assume someone conforms to my assumptions of who they are rather than learning what the reality is. A Catholic, for example, could be a Benedictine monk or a ultra-liberal or SSPX or who knows what. It is only when you push past the stereotype that you can get to know them. Others, of course, never want to deal with anything except the stereotype. Sum me up in two seconds, slam me up against the wall with a quickie quote, and then move on.
Some people are also in transition and do not want to admit it. Struggling with doubts and in between bar stools. They would look at that religious designation and say “that’s a lie but I don’t want anyone to know that I am no longer X”.
That being said, people should be able to have a short biography of “this is who I am”. Purely optional.