Leaving aside the idiocy of the first part of your remark, has anyone suggested that Caiaphas (not Caiaphus, by the way) was fictional? No-one is arguing that the setting of the story was made up (though if it was shown to be so, that of course would cast more doubt on the other parts of the NT (did someone say "census"?)); when we talk of the truth of the New Testament, we're talking about the supernatural parts, since it doesn't mean much either way if the mundane parts are true or not. However, there doesn't appear to be a shred of corroboration for the miracles, or some of the other events one might think worthy of comment; several thousand speaking in tongues, and converting to a new religion (mysteriously to disappear and never be heard from again), or the dead walking the streets of Jerusalem, for example; no independent account of these. Really?
The Romans, and Caesar Augustus are also mentioned in the bible; I haven't heard anyone seriously suggest that they didn't exist; though there was one guy who seemed to think there was doubt whether Julius Caesar existed...