It might just be a thing but I'm surprised by the number of people I know who select the religion they were christened as even though they clearly say they don't believe in God or any higher being. My wife used to do that and most of her family still do the same even though they don't believe, it's almost like they think being christened is some sort of life long commitment even though you don't get a say in it at the time.

Youth may be over-represented as religious as well. My parents are Christians and used to put me as the same on the census even though I thought it was a crock from a fairly early age, and for the few years that I filled it out but still lived at home I did the same to "keep the peace" and avoid any additional bible bashing.