I think a lot of people are secular or only slightly religious, but still hold on to their religious roots. As a result, they may not be as knowledgeable as someone that is more religious.
For example, "Christmas Christians" and "Easter Christians" are people that celebrate those holiday and go to the Christmas Eve and Easter services, but dont engage in the church community or pursue their faith in any other fashion throughout the rest of the year. They may believe in the Christian God and follow main tenets, but dont take religion super seriously. These people usually aren't as knowledgeable in theology and traditions as a result.
Im not making a moral judgement here. Im just answering his question. :D