A central belief of Christianity is that Jesus is divine, the Son of God. But, how do we know Jesus himself made that claim and how can we know if it's true? There are several places in the New Testament recording Jesus' claims that he was divine, including:
"I am the bread of life. I came down from heaven. For this is the will of my Father, that everyone who sees the Son and believes in him may have eternal life. The living Father sent me." (John 6:35, 38, 40, 57 NAB)
Again the High Priest questioned him, "Are you the Messiah, the Son of the Blessed God?" "I am," answered Jesus. (Mark 14:61-62 TEV)
A common counter-argument is that Jesus himself did not make these claims of divinity, but these words were later "put in his mouth" by his overzealous followers. If that is the case, how do we explain why Jesus was crucified? For if Jesus was not crucified for blasphemy (claiming to be God), then why did the Jewish leaders want him killed? It is difficult to explain Jesus' crucifixion, which is a well-attested historical fact, if he did not actually claim to be God.
Since Jesus claimed to be divine, he was either telling the truth, or he was a deliberate liar (he knew his claim was false), or he was sadly delusional (he though he was God, but was not). As C.S. Lewis noted in his book Mere Christianity, for Jesus to have talked as he talked, lived as he lived, and died as he died, he was either a boldfaced liar, an insane lunatic, or truly our Lord and God. So, was Jesus a liar, a lunatic, or our Lord?
What would Jesus have gained by dying for a lie? People do not give up their lives for what they know to be a lie. Furthermore, even non-Christians agree that Jesus was a great moral teacher, a good and wise person. Jesus talked about love, healed the sick, defended the poor and cared for the outcast. Who but a good and wise person does that? However, a liar is not a good person. A liar is the opposite of good. A lunatic is the opposite of wise.
Again, suppose it was Jesus' disciples who invented the lie. What motive would they have for doing this? What liar would suffer torture and death for what they knew to be a lie? This makes no sense. Instead, they proved their sincerity by their martyrdom.
However, could Jesus have been delusional and deceived his disciples? After all, there are many lunatics in asylums who sincerely believe they are God. The character traits of the "divinity complex" are well known: egotism, narcissism, inflexibility, dullness, and an inability to understand and love others. Would thousands of people follow such a person, many to their death? Would you?
Furthermore, how could the Apostles have been so successful in gaining followers and fostering the transformed lives of so many people from so many places if they were just naive fools who had been deceived by Jesus? And, is it realistic to expect that all of the Apostles would have been continually deceived? For not one of them ever denied what they believed to be true. It is unrealistic to expect that they and thousands of people throughout the centuries would willingly suffer torture and death if what they believed was indeed a false deception. Insane or delusional people just aren't this widely successful for so long. It's hard to expect that a deliberate lie or false delusion would have "withstood the test of time" for twenty centuries without being clearly exposed as such.
Of course, anyone claiming to be divine must have some pretty solid evidence to back up their claim in order to be taken seriously. What evidence is there that caused Jesus' claim of divinity to be taken seriously, including by those who wanted him crucified?
First, the originality and authority of Jesus' teachings, especially his parables, is evidence of his divinity. Who else has told so many profoundly insightful stories, in such an impromptu manner, that are still relevant two thousand years later? Anyone hearing or reading the parables of Jesus cannot help but marvel at the "superhuman" creativity and wisdom of their author.
Jesus' many miracles are also evidence of his divinity. In addition to his teachings, it was his miracles that drew huge crowds. If the miracles did not actually happen, would so many people have been drawn to him?
Finally, Jesus' Resurrection is the most compelling evidence of his divinity. The radically transformed lives of his followers after the Resurrection confirm its validity. Before the Resurrection they were scared and timid, afterwards they couldn't stop boldly proclaiming the "good news" that Jesus was indeed God and that he suffered and died for the salvation of all.