Religion

or who claim to belong to a church (or other organization, for that matter) but who really don't believe in its purpose or care about it at all, who just joined and/or maintain a nominal membership as a result of family or social pressures. You go to church as a kid to keep from being pestered about it; when you're older you might keep going because the rest of your family does, or your neighbors and friends do and you don't want to be the odd person out. And I assume all these lukewarm or nominal members are counted.