Fairly often I get into religious conversations with people and end up asking them what their faith background is. Most recently, I was talking to a guy at work and he told me that he was a Christians and then he went on to describe some of his theological beliefs. I was a little surprised because I would not have guessed he was a Christian.
Lots of people are like this...when asked, they claim Christianity, but their behavior and speech don't reflect it; they aren't working the way God intends them to...in other words, they aren't properly functioning Christians.