The Christological argument for the existence of God, which exists in several forms, holds that if certain claims about Jesus are valid, one should accept that God exists. There are three main threads; the argument from the wisdom of Jesus, the argument from the claims of Jesus as son of God and the argument from the resurrection.
Argument from the wisdom of Jesus
The essential structure of this argument is as follows: The character and wisdom of Jesus is such that his views about reality are (or are likely to be) correct. One of Jesus' views about reality was that God exists. Therefore, the view that God exists is (or is likely to be) correct.
Some forms of evangelism take this approach. Potential converts are introduced to Jesus as a historical character and the merits of Jesus' teachings are discussed. In such a context, the historicity of Jesus is a crucial factor in assessing the argument.
The principal objections to (1) are the suggestions that: The reports of Jesus' character in the Bible are not reliable. Jesus' views about reality are not (or not likely to be) necessarily correct. Bertrand Russell, in his essay "Why I Am Not a Christian", criticized Jesus' personal character and philosophical positions on various grounds. Even supposing that Jesus was correct, wise, and knowledgeable about a great many things does not imply that he was knowledgeable about everything. A deep knowledge of moral philosophy and the iniquities of the human condition, for example, do not necessarily imply any valid expertise on astrophysics, Phoenician literature, or the literal existence of God.
Argument from the claims of Jesus to divinity
Lewis's trilemma is an apologetic argument traditionally used to argue for the divinity of Jesus by arguing that the only alternatives were that he was evil or deluded. One version was popularised by University of Oxford literary scholar and writer C. S. Lewis in a BBC radio talk and in his writings. It is sometimes described as the "Lunatic, Liar, or Lord", or "Mad, Bad, or God" argument. It takes the form of a trilemma — a choice among three options, each of which is in some way difficult to accept.
This argument is very popular with Christian apologists, although some theologians and biblical scholars do not view Jesus as having claimed to be God. Some argue that he identified himself as a divine agent, with a unique relationship to Israel's God. Others see him as wanting to direct attention to the divine kingdom he proclaimed.
The argument relies on the premise that Jesus was a great moral teacher. The structure of the argument is as follows: Jesus claimed to be God Jesus was a wise moral teacher By the trilemma, Jesus was dishonest, deluded or God No wise moral teacher is dishonest No wise moral teacher is deluded By 2 and 4, Jesus was not dishonest By 2 and 5, Jesus was not deluded By 3, 6 and 7, Jesus was God By 8, God exists
Those who dispute these premises suggest that: Disputing premise 1: Jesus was indeed a wise moral teacher, but his reported teachings have been distorted or misrepresented. For instance, he may not have actually claimed to be divine; this claim may have been added by later writers. Many modern New Testament scholars argue that Jesus did not, in fact, claim to be God. Disputing premise 2: C.S. Lewis expressed the opinion that any mere man who claimed to be God could not, by definition, be a wise moral teacher (and that, conversely, any wise moral teacher would not claim to be God). Christopher Hitchens argued that Jesus was not a wise moral teacher by arguing against several of his teachings. For example, of Jesus' teaching "Let him who is without sin cast the first stone", Hitchens wrote: "if only the non-sinners have the right to punish, then how could an imperfect society ever determine how to prosecute offenders?" Disputing premise 4: A person can be a wise moral teacher despite lying. Jesus could have believed (as some later philosophers have held) that religion is false but beneficial to society, and that by establishing a new religion (or a reform of Judaism) he was doing a good deed nonetheless. Disputing premise 5: A person can be a wise moral teacher despite being delusional. Granting credence to some, or even most, of someone's claims does not require that we give credence to all of them. Someone can believe Socrates' philosophical claims about justice without also believing Socrates' theological speculations about the Greek gods, or accept Aristotle's views on poetry without also accepting his claim that heavier objects fall faster than lighter ones.