This is perhaps the greatest syllogism I have ever read regarding Jesus and the Bible. I think it is crucial to read and think about this especially in the morally bankrupt society we live in today.
Wikipedia describes the trilemma this way.
Lewis's Trilemma (or the Lewis Triumvirate) is a syllogism intended to prove the logical inconsistency of both holding Jesus of Nazareth to be a "great moral teacher" while also denying his divinity. It was first published by Clive Staples "Jack" Lewis in a BBC radio interview.
The trilemma is often summarized either as "Lunatic, Liar, or Lord", or as "Mad, Bad, or God". The premises are as follows.
(P): Jesus claimed to be God.
(Q): One of the following must be true.
1. Lunatic: Jesus was not God, but he mistakenly believed that he was.
2. Liar: Jesus was not God, and he knew it, but he said so anyway.
3. Lord: Jesus is God.
From these premises, Lewis argued, it follows logically that,
(C): If not God, Jesus is either not great or not moral.
Lewis' argument has often been adapted for apologetic use in the form,
(A): If the records of Jesus' teaching are accurate, he is Lunatic, Liar or the Lord he claims to be.
CS Lewis used this as the basis of his book Mere Christianity saying,
"I am trying here to prevent anyone saying the really foolish thing that people often say about Him: I’m ready to accept Jesus as a great moral teacher, but I don’t accept his claim to be God. That is the one thing we must not say. A man who was merely a man and said the sort of things Jesus said would not be a great moral teacher. He would either be a lunatic — on the level with the man who says he is a poached egg — or else he would be the Devil of Hell. You must make your choice. Either this man was, and is, the Son of God, or else a madman or something worse. You can shut him up for a fool, you can spit at him and kill him as a demon or you can fall at his feet and call him Lord and God, but let us not come with any patronising nonsense about his being a great human teacher. He has not left that open to us. He did not intend to. ... Now it seems to me obvious that He was neither a lunatic nor a fiend: and consequently, however strange or terrifying or unlikely it may seem, I have to accept the view that He was and is God."
