Every Sunday, I attend the Latin mass at a conservative Catholic church. For the past several weeks, the priest has been doing a series on apologetics, in which he's given arguments for the Catholic faith's credibility. Last Sunday, he said that Jesus' words are proof of Christianity's validity. "But why should we trust what Jesus says?" he foresaw the skeptic asking. His response was C.S. Lewis' "Lord, liar, lunatic" argument.
In Mere Christianity, C.S. Lewis addresses the view that Jesus was merely a good moral teacher, as opposed to being God incarnate. Lewis argued that, if Jesus were not who he said he was (God), then he was hardly a good moral teacher, but rather a madman or a liar. Lewis didn't think that Jesus was the latter two because he said good things and seemed to be stable. Therefore, he concluded that Jesus was who he said he was: God incarnate.
The priest elaborated on some of Lewis' points. He tried to show from the Gospels that Jesus was not insane. According to the priest, Jesus did not demand worship from the Jews, as would a madman; instead, he only revealed his divinity to his closest associates. The priest also pointed out that Jesus was not a radical revolutionary, for he was a humble carpenter. For the "liar" option, the priest disputed that Jesus was lying because he laid down his life, and people are not willing to die for a lie.
The priest then added two other options: myth and non-Christian. In response to those who say that Jesus did not exist, he asserted that there is more proof for Jesus as a historical figure than there is for Julius Caesar. Then, he addressed the claim that Jesus didn't want to start the church. According to the priest, the Gospels say that Jesus did have such a desire, and they are the only records we have of what Jesus taught. The priest dismissed the Gnostic Gospels by saying that they were late and heretical.
I have mixed feelings about the "Lord, liar, lunatic, myth, non-Christian" argument. On the one hand, I like its "take it or leave it" approach. Regarding Jesus only as a moral teacher divorces his teachings from his authority. Without Jesus' divine authority, what is the basis for his teachings? Sure, there are beneficial effects to loving our neighbor, but why should we regard Jesus' view of God and religion as superior to other opinions (e.g., those of the Pharisees in the Gospels), if he indeed lacks divine authority?
On the other hand, if I were a skeptic, the "Lord, liar, lunatic, myth, non-Christian" argument would not particularly convince me. There are plenty of people who believe grandiose things about themselves, and yet they are not necessarily madmen or liars. In fact, some of their teachings sound pretty good. The Dalai Lama is an example. I would say the same about Mohammad. He was sane enough to run a business. He risked persecution, which (according to the standards of Christian apologists) should show that at least he thought he was telling the truth. And he stood up for social justice in Mecca.
Moreover, I thought that the priest was being pretty selective when he was discussing Jesus' sanity. He said that Jesus only revealed his divine identity to his closest disciples. Sure, if you just read the synoptic Gospels. In Matthew, Mark, and Luke, Jesus often does conceal his messianic and divine identity from the masses. In John, however, Jesus is a lot more public about his divine status, to the point that many of his hearers actually question his sanity (see John 8). Yes, Jesus was a humble carpenter who socialized with publicans, sinners, and Pharisees, as the priest pointed out. But he was also a revolutionary who challenged many of the social and religious customs of his day. And he could be quite rigid on occasion. In Matthew 12:30, he says, "He that is not with me is against me; and he that gathereth not with me scattereth abroad." No middle ground? If I were standing there at the time, my thought would have been, "Who's this fanatic?"
So my reason for believing in Jesus is not that he meets our standards of sanity or propriety. As a matter of fact, some of his statements appear rather bizarre! But they do make sense, from a certain point of view.