The Lord, Liar, Lunatic trilemma has been proposed by several Christian apologists, including the noted layman’s theologian C. S. Lewis. It seeks to argue that Jesus Christ was Lord, Savior, and all those other wonderful things he said he was in the New Testament. It goes about this by proposing something of a trilemma regarding Jesus:
Assuming that Jesus existed, and that he said he was the Lord, there are three possibilities regarding his claims: what he said was either (1) true—he was LORD; (2) false because he was a lying; or (3) false because he was insane, as only a lunatic would believe that he were the son of God if it were not true. Since his words are very profound, they can hardly be discounted as the words of a raving lunatic. He could not have been a liar because he was willing to die for his beliefs, as were many of his followers; this hardly seems like the acts of a liar. Therefore, since the other two options have been eliminated, he must have been LORD.
There are a number of flaws with this argument, starting at the most fundamental level of the assumptions. The assumptions need not be accepted at all; there are a number of other options. If the historical figure of Jesus did not exist at all (which is possible, but not necessarily plausible), then the argument is superficially ludicrous. If Jesus did exist, then he may not have ever said he was LORD, but rather the early Christians such as St. Paul and the New Testament Gospel authors merely fit his person to their Messiah god Xristos. One possible scenario, for instance, is that he never said he was LORD in the sense that Christians mean it, but was merely a Jewish religious reformer and faith-healer, who called himself by names which have been misinterpreted by later Christians (“Son of God” is a common term in Jewish religious literature for people who are very important to God, such as King David) and that his teachings were encrusted and embellished with miraculous life narratives and salvation myths as his followers shifted from the original Jewish reformers to the apocalyptic mystery cult of Christianity.
The next significant flaw is that of a false trichotomy: the argument proposes only three options when there are in fact more. One of the most likely is that Jesus’s followers sincerely believed what they said, but were not correct. Falsities could be introduced into the record by any number of means other than direct lying or insanity; exaggerated tales transmitted through the oral record, confusions of parables with actual events (such as with the fig tree incident, which is portrayed in one Gospel as an actual act of Jesus and in another as a parable), and interpolations introduced by Gospel authors who were more concerned with religious inspiration than historical accuracy may all play a large role in what has come to us as the stories of Jesus’s life. It is quite possible that, whether Jesus ever said anything about being LORD or not, St. Paul and the various other authors of early Christian books sincerely believed that Jesus was the Messiah in the form of Xristos.
The final significant flaw in this argument is that it seeks to eliminate the options of liar and lunatic, but fails to do so adequately. The argument simply dismisses them out of hand without any particularly objective standard. If Jesus was delusional as to his godhood, that does not in anyway preclude his abilities to make profound moral and religious observations; delusions of godhood do not rule out functional sanity in other fields of life, and even were he totally insane there are still several cases of insane or marginally loony people putting out observations that seem profound to some (E.G. Friedrich Nietzsche, who produced his final works the last year before he became clinically insane). The argument against liar is even less convincing; there is no reason to presume that Jesus or the early Christians deliberately acted knowing that they would die for it, and even had they, history has been littered with people making huge sacrifices for liars and lunatics. David Koresh, L. Ron Hubbard, Jim Jones, and the many other founders and leaders of lunatic-fringe cults could all be defended on the same grounds as Jesus, since there is no standard other than personal incredulity given for dismissing the options of liar and lunatic.
In fact, the argument could just as easily be applied to most other would-be prophets and saviors. Many have fought and died for Muhammed, and his moral teachings could be argued to be as profound as those of Jesus. Somehow I doubt, however, that our friendly apologist will rush into submission to the Will of Al-Lah.