Generalization of credibility

There's a very simple concept that nobody should have any difficulty in accepting: Just because a writing mentions some things that are demonstrably factual, that doesn't automatically mean that everything that's written there is factual.

There's absolutely nothing controversial or strange about this, and it should be quite easy to accept. A work of fiction is the most prominent example: Many works of fiction talk about real places and real events, yet also talk about completely fictional people, events and places. For example, if a book talks about real cities like London or New York, that doesn't give any kind of credibility to what the same book says about, for example, vampires or werewolves.

This is such a simple concept that even a small child ought to understand it. Yet many Christians seem completely incapable of this.

When asked how can we know that what the Bible says is true, they will almost invariable resort to pointing out the few parts of it that are easy to accept. They will point out how, for example, archaeology confirms many of the events and places depicted in the Bible. They will point out things that the Bible says that happen to be true (a good example is the concept of washing hands helping to prevent diseases from spreading.)

For some reason they seem to be incapable of understand the simple concept that simply because a book talks about real places and real events, that doesn't mean that everything that the book claims is true. Yet they use this argument all the time.