I think that Nogodsforme is correct in that the Bible, in itself, is a stumbling block for many, if not most Christians, and that the argument could definitely be made that this is a good thing.
The way I see it, these Christians, including Old Church Guy, are more Theists with Christian trappings. They are those genetically "wired" for faith; they need a higher power to believe in, and naturally the religion they were brought up with and is most prevalent in their surroundings "feels" right. So that's how they identify, whether they strictly embrace every last bit of dogma or not. Delving deeper into it raises uncomfortable questions, which creates a market for books and philosophies which manage to find the warm and fuzzy interpretations, focusing on the lessons in love and forgiveness and sugar-coating, downplaying, or downright rejecting the notion of eternal torment for the unbeliever. Yet they still identify as Christian because for the most part it's a comfortable niche where they can practice their faith with more or less like-minded people.
While the argument could be made that they are not "Christians" because of this, they are also, often, the people more "Christ-like" in their attitude toward others. They find the lessons of love and forgiveness more compelling in a god-figure than they do jealousy and vengeance. They follow the philosophies attributed to Jesus according to their hearts and cannot comprehend or reconcile the idea of a loving god with that of hell.
Others seem to find more security in a much narrower definition, where they do not believe that those who waffle about details merit salvation. As long as they, themselves, think their path leads to heaven, their god seems perfectly justified in his criteria.