Lewis's trilemma is an argument intended to prove the divinity of Jesus. It was the proposal of a trilemma (mentioned by others the previous century) that was popularised by C. S. Lewis in a BBC radio talk and in his writings. It is sometimes summarized either as "Lunatic, Liar, or Lord", or as "Mad, Bad, or God".
This argument was widely cited in various forms in the nineteenth century. It was used by the American preacher Mark Hopkins in his book Lectures on the Evidences of Christianity (1846), based on lectures delivered in 1844. Another early use of this approach was by the Scots preacher "Rabbi" John Duncan (1796–1870), around 1859-60:
"Christ either deceived mankind by conscious fraud, or He was Himself deluded and self-deceived, or He was Divine. There is no getting out of this trilemma. It is inexorable."
C. S. Lewis was an Oxford medieval historian, popular writer, and Christian apologist. He used the argument outlined below in a series of BBC radio talks later published as the book Mere Christianity.
"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."
Lewis's trilemma is based on the view that, in his words and deeds, Jesus was asserting a claim to be God. For example, in Mere Christianity, Lewis refers to what he says are Jesus' claims:
- to have authority to forgive sins—behaving as if he really was "the person chiefly offended in all offences."
- to have always existed, and
- to intend to come back to judge the world at the end of time.
Lewis implies that these amount to a claim to be God and argues that they logically exclude the possibility that Jesus was merely "a great moral teacher", because he believes no ordinary human making such claims could possibly be rationally or morally reliable. Elsewhere, he refers to this argument as "the aut Deus aut malus homo" ("either God or a bad man"), a reference to an earlier version of the argument used by Henry Parry Liddon in his 1866 Bampton Lectures, in which Liddon argued for the divinity of Jesus based on a number of grounds, including the claims he believed Jesus made.
The trilemma has continued to be used in Christian apologetics since Lewis, notably by writers like Josh McDowell. Peter Kreeft describes the trilemma as "the most important argument in Christian apologetics" and it forms a major part of the first talk in the Alpha Course and the book based on it, Questions of Life by Nicky Gumbel. Ronald Reagan also used this argument in 1978, in a written reply to a liberal Methodist minister who said that he did not believe Jesus was the son of God. A variant has also been quoted by Bono. The Lewis version has been cited by Charles Colson as the basis of his conversion to Christianity. Stephen Davis, a supporter of Lewis and of this argument, argues that it can show belief in the Incarnation as rational.
Writing of the argument’s “almost total absence from discussions about the status of Jesus by professional theologians and biblical scholars”, Davis comments that it “is often severely criticized, both by people who do and by people who do not believe in the divinity of Jesus”.
A frequent criticism is the claim that the statements and actions referred to by Lewis were an invention of the early Christian movement, seeking to glorify Jesus. According to Bart Ehrman, 'there could be a fourth option – legend'. Lewis himself denied the accounts of Jesus were legends: "I have read a great deal of legend and I am quite clear that they are not the same sort of thing".  N. T. Wright, a leading New Testament scholar, comments that Lewis's argument "doesn't work as history, and it backfires dangerously when historical critics question his reading of the Gospels."
The trilemma rests on the interpretation of New Testament authors' depiction of Jesus: a widespread objection is that the statements by Jesus recorded in the Gospels are being misinterpreted, and do not constitute claims to divinity.
In a criticism of Lewis's approach in his bestselling 1963 book, Honest to God, John A. T. Robinson, then Bishop of Woolwich, questioned the idea that Jesus intended to claim divinity: "It is, indeed, an open question whether Jesus claimed to be Son of God, let alone God". John Hick, writing in 1993, argued that this 'once popular form of apologetic' was ruled out by changes in New Testament studies, citing 'broad agreement' that scholars do not today support the view that Jesus claimed to be God, quoting as examples Michael Ramsey (1980), C. F. D. Moule (1977), James Dunn (1980), Brian Hebblethwaite (1985) and David Brown (1985). According to Gerd Lüdemann the broad consensus among a number of New Testament scholars is that the proclamation of the divinity of Jesus was a development within the earliest Christian communities. Larry Hurtado, who argues that the followers of Jesus within a very short period developed an exceedingly high level of devotional reverence to Jesus, at the same time rejects the view that Jesus made a claim to messiahship or divinity to his disciples during his life as 'naive and ahistorical'. N. T. Wright says the 'trilemma' argument lacks historical context, oversimplifying first century Judaism's understanding of the nature of God's dealings with his people. Wright points out that arguments over the claims of Jesus regarding divinity have been passed over by more recent scholarship, which sees a more complex understanding of the idea of God in first century Judaism.
Invalid logical form
Another criticism raised is that Lewis is creating a false trilemma by insisting that only three options are possible. Philosopher John Beversluis comments that "he deprives his readers of numerous alternate interpretations of Jesus that carry with them no such odious implications". Philosopher and theologian William Lane Craig cites this as a reason why he believes it is an unsound argument for Christianity. Peter Kreeft and Ronald Tacelli, SJ - both professors of philosophy at Boston College - have expanded the argument into a tetralemma ("Lord, Liar, Lunatic or Legend") — or a pentalemma, accommodating the option that Jesus was a guru, who believed himself to be God in the sense that everything is divine.
- Mark Hopkins, Lectures on the Evidences of Christianity (1846), Lecture VIII: 'either ... those claims were well-founded, or of a hopeless insanity. ... No impostor of common sense could have had the folly to prefer such claims.'
- William Knight, Colloquia Peripatetica, 1870, page 109: Knight explains that the conversations quoted took place during the summers of 1859 and 1860.
- Undated sermon by R. A. Torrey, Billy Graham archives; see also Deity of Jesus Christ, by R. A. Torrey, 1918
- W. E. Biederwolf, "Yes, He Arose", in Great Preaching on the Resurrection: Seventeen Messages, ed. Curtis Hutson, Sword of the Lord Publishers (1984), page 29.
- Lewis, C.S., Mere Christianity, London: Collins, 1952, p54-56. (In all editions, this is Bk. II, Ch. 3, "The Shocking Alternative.") Forty years earlier, G. K. Chesterton used a similar argument about someone else in his The Napoleon of Notting Hill (1904), where Adam Wayne is described this way: "He may be God. He may be the Devil. But we think it more likely as a matter of human probability that he is mad." See Cecil Chestrton, G. K. Chesterton: A Criticism (Seattle: Inklng, 2007), 26.
- C S Lewis,Mere Christianity, Simon & Schuster. p. 55.
- Compare G. K. Chesterton, The Everlasting Man
- Mark 2:1–12 is the most common of several passages interpreted this way.
- Probably a reference to John 8:58: "Jesus said to them, ‘Very truly, I tell you, before Abraham was, I am.’"[John 8:58]
- Lewis, C.S., Mere Christianity, London: Collins, 1952, p. 51.
- C. S. Lewis, God in the Dock: Essays on theology and ethics, 1945, Eerdmans, p101; letter to Owen Barfield, c. August 1939, printed in Walter Hooper (ed.), The Collected Letters of C. S. Lewis, Volume 2, Harper Collins (2004), page 269
- Henry Parry Liddon, The Divinity of Our Lord and Saviour Jesus Christ, Lecture IV (London, 1867): Liddon's version was 'Christus si non Deus non bonus'. According to Charles Gore, (The Incarnation of the Son of God, (1890), Liddon could not recall the source of the epigram but Gore thought it went back to Victorinus Afer. (Appendices, page 238)
- Kreeft, Peter (1988). Fundamentals of the Faith: Essays in Christian Apologetics, p. 59. San Francisco, Ignatius Press. ISBN 0-89870-202-X. Chapter excerpted online, accessed 13 April 2007.
- Helene von Damm, ed., Sincerely, Ronald Reagan (New York: Berkley, 1980), 90
- Michka Assayas, Bono in Conversation, (Riverhead Hardcover, 2005) page 205.
- Jonathan Aitken, Charles Colson, (Continuum International, 2005), pages 210-211.
- "In this chapter, C.S. Lewis’ famous trilemma argument in favour of the divinity of Christ (Jesus was either mad, bad, or God) is developed, and a version of it is defended.","Was Jesus Mad, Bad, or God?", Davis (2006),Stephen T, Christian Philosophical Theology, Oxford University Press, Abstract,Ch.9,p149f.
- Craig L. Blomberg describes this view: "The problem with this argument is that it assumes what is regularly denied, namely, that the gospels give entirely accurate accounts of the actions and claims of Jesus ... This option represents the most common current explanation of the more spectacular deeds and extravagant claims of Jesus in the gospels.' Craig L. Blomberg, The Historical Reliability of the Gospels, (Intervarsity Press, 1987), page xx.
- Quoted by Neely Tucker, "The Book of Bart", Washington Post 5 March 2006 
- What Are We to Make of Jesus Christ? 
- Wright, N. T. (March 2007). "Simply Lewis: Reflections on a Master Apologist After 60 Years". Touchstone Magazine 20 (2). Retrieved 2009-02-11.
- John A. T. Robinson, Honest to God, 1963, page 72.
- John Hick, The Metaphor of God Incarnate, page 27: : "A further point of broad agreement among New Testament scholars ... is that the historical Jesus did not make the claim to deity that later Christian thought was to make for him: he did not understand himself to be God, or God the Son, incarnate. ... such evidence as there is has led the historians of the period to conclude, with an impressive degree of unanimity, that Jesus did not claim to be God incarnate."
- Gerd Lüdemann, "An Embarrassing Misrepresentation", Free Inquiry, October / November 2007: "the broad consensus of modern New Testament scholars that the proclamation of Jesus's exalted nature was in large measure the creation of the earliest Christian communities."
- Hurtado, Larry W. (2005). How on earth did Jesus become a god?: historical questions about earliest devotion to Jesus. Grand Rapids, Mich.: W.B. Eerdmans Pub. Co. pp. 4–6. ISBN 0-8028-2861-2.
- Hurtado, Larry W. (2005). Lord Jesus Christ: Devotion to Jesus in Earliest Christianity. Wm. B. Eerdmans Publishing Company. p. 5. ISBN 0-8028-3167-2.
- Wright, N. T. (1999). The challenge of Jesus : rediscovering who Jesus was and is. Downers Grove, Ill.: InterVarsity Press. p. 98. ISBN 0-8308-2200-3.
- John Beversluis, C.S. Lewis and the Search for Rational Religion (Grand Rapids: Eerdmans, 1985), p 56.
- William Lane Craig, Reasonable Faith: Christian Truth and Apologetics, Crossway Books (1994) pages 38-39.
- Peter Kreeft and Ronald Tacelli, Handbook of Christian Apologetics, (Madison, 1994), 161-174.