I saw a sign at my local shopping centre about our recent census debacle (brought to you by debacle central - the Australian Public Service - with assistance from IBM.
The census invited us to tell which of about a dozen 'religions' we adhered to. It was optional to answer.
The sign urged those with no express religious affiliation to mark 'no religion', rather than repeat a remembered family or parental affiliation.
Then I reflected on my own answer on the by then operative website. First I marked an affiliation. Then pondered. Heck, I don't want the government knowing something so personal and so irrelevant to government about me. I want to un click the box I'd clicked. No could do. I had to now click something else. So I did 'other' and described my 'other' as 'optional'.
Worked for me, and none of their business.