- The Church of The Holy Sepulcher holds a Holy Fire ceremony every year at the tomb of Jesus in Jerusalem, Israel. -
The Best Evidence for the Existence of Jesus
There is no one more famous on Earth or in history than Jesus Christ of Nazareth, according to his own words he was God in human form.  And various prophets and apostles described Jesus in the exact same way throughout the Bible.  The religion that Jesus began with his death and resurrection has grown to the largest religion in the world, exactly as he prophesied.  In addition to this incredible prophesy that has already come to pass, Jesus gave us another prophesy that is on the cusp of coming true.
In Matthew 24:14, Jesus tell us how to tell how far we are from the end of the world. "And this gospel of the kingdom will be preached in the whole world as a testimony to all nations, and then the end will come." If Jesus was anything other than God in human form, he would not have accurately predicted that his religion would become the largest in the world, or that his message would be preached in all nations. Perhaps even more interesting, is that the Gospel is close to being preached in all nations, however it has not reached everyone. Logically this would mean we are not far off from the end of the world, but an exact time frame until that happens cannot be established perfectly.
Prophesy that we can verify in our modern times can be an excellent way to test if Jesus was who he said he was. In fact, God actually had his people use prophesy about future events in the Old Testament to verify if a prophet was really from God or not.
You may say to yourselves, “How can we know when a message has not been spoken by the Lord?” If what a prophet proclaims in the name of the Lord does not take place or come true, that is a message the Lord has not spoken. That prophet has spoken presumptuously, so do not be alarmed.
We can apply this test to Jesus and find that just the one prophesy of Christianity becoming the largest religion in the world  fulfills the Old Testament requirement for a confirmed prophet of God. However this was far from the only fulfilled prophesy Jesus made. He prophesied that wherever the Gospel was preached in the world, the story of Mary of Bethany would be told with it.  Indeed her story has been told throughout the world as it is in all four of the Gospel books. Jesus also predicted his own betrayal by Judas , the exact day of his death and that it would be by crucifixion , that he would resurrect from the dead on the third day , that Jerusalem and the temple would be destroyed within one generation because they murdered the Messiah , that the Jewish people would be displaced from their homeland and then be returned , that the Holy Land would be ruled by Gentiles while the Jews were displaced , the Jewish people would experience terrible persecution.  There are many more prophecies that Jesus gave that were fulfilled, more than any other prophet recorded.
Although prophesy is an excellent way to confirm that Jesus was who the writers of the New Testament said he was, we can also find evidence through other more conventional means. The historical method is a series of techniques and guidelines that allow a researcher to construct an accurate picture of past events. It is the equivalent of the scientific method for historians. 
There is very strong evidence in the historical record for the existence of Jesus Christ of Nazareth, and virtually all historical scholars agree he existed. [14-16] Although the portraits of the historical Jesus vary in their scope, generally they agree that Jesus was a Jewish preacher who taught that he was the path to salvation, everlasting life, and the Kingdom of God.  Although the Bible is powerful evidence, there are many non-Biblical sources that mention Jesus. Some of these include the Samaritan historian Thallos , the Jewish historian Flavius Josephus , the Roman historian Tacitus , the Roman satirist Lucian of Samosata , the Jewish Talmud , and the Roman writer Mara bar Serapion.  Some of these sources agree with the Bible and claim that Jesus was truly God in human form, however some disagree. However it is those that disagree with Jesus' teachings that can actually be more powerful in confirming that he was a real person in history and not just a legend.  The historical method calls this a biased source, which means that it has a higher probability of being true since the source would have gained nothing by lying.  Just the Roman historian Tacitus' account in Annals is enough by itself to confirm the existence of a real man name Jesus in history, because of the overtly negative tone. 
The miracles Jesus performed in the Gospels were done with the express purpose of demonstrating that he was the prophesied Messiah and creator of the universe. Any historical evidence of the four Gospel accounts of the miracles would help to verify that Jesus really performed them. Some of the accounts that confirm the miracles of Jesus besides the Bible are as follows:
The Jewish historian Flavius Joseph wrote in The Antiquities of the Jews, 
"Now there was about this time Jesus, a wise man; if it be lawful to call him a man. For he was a doer of wonderful works; a teacher of such men as receive the truth with pleasure. He drew over to him both many of the Jews, and many of the Gentiles. He was the Christ. And when Pilate, at the suggestion of the principal men among us, had condemned him to the cross; those that loved him at the first did not forsake him. For he appeared to them alive again, the third day: as the divine prophets had foretold these and ten thousand other wonderful things concerning him. And the tribe of Christians, so named from him, are not extinct at this day."
Julius Africanus quotes Thallos on the miracle of the darkness and earthquakes during Jesus' death, in Chronography. 
“On the whole world there pressed a most fearful darkness; and the rocks were rent by an earthquake, and many places in Judea and other districts were thrown down. This darkness, Thallos, in the third book of his History... appears to me without reason, an eclipse of the sun.”
Mara Bar-Serapion referenced Jesus's prophesied destruction of the city of Jerusalem, which he claimed happened because Jesus was rejected by the Jewish people.
"What benefit did the Athenians obtain by putting Socrates to death? Famine and plague came upon them as judgment for their crime. Or, the people of Samos for burning Pythagoras? In one moment their country was covered with sand. Or the Jews by murdering their wise king?…After that their kingdom was abolished. God rightly avenged these men…The wise king…lived on in the teachings he enacted.” 
In addition to the evidence here, there are many Old Testament prophecies for Jesus which also demonstrate his credibility. In our modern age of scientific advancement we cannot use the scientific method to test Jesus in any way yet devised. But we can use the historical method to show there is strong evidence for everything the Gospels claimed including the miracles Jesus performed, since trustworthy extra-biblical sources reference them. And we can know that Jesus is God in human form, not just because he told us, but because he was able to predict the future without ever making a single mistake. No supposed spiritual leader in any major religion besides Christianity and Judaism can make that claim.
1. Matthew 28:19, John 8:58, John 10:30, John 10:33
2. Matthew 1:23, Mark 2:5-7, John 1:1, John 1:18, John 5:18, John 10:30, John 17:21, John 20:27-29, Philippians 2:5-7, Colossians 1:15, Colossians 2:9, 2 Peter 1:1, Hebrews 1:3,
3. Matthew 13:31–32
5. Matthew 26:6–13; Mark 14:3–9; Luke 7:36–50; John 12:1–8
6. Matthew 26:21-22
7. Matthew 26:2
8. John 2:18-22
9. Matthew 24:1,2 and Matthew 24:34 | Luke 19:41-44 and Luke 21:20
10. Luke 21:24
11. Luke 23:28-30
12. Gilbert J. Garraghan and Jean Delanglez A Guide to Historical Method p. 168
13. Thurén, Torsten. (1997). Källkritik. Stockholm: Almqvist & Wiksell.
14. In a 2011 review of the state of modern scholarship, Bart Ehrman (a secular agnostic) wrote: "He certainly existed, as virtually every competent scholar of antiquity, Christian or non-Christian, agrees, based on certain and clear evidence." B. Ehrman, 2011 Forged: writing in the name of God ISBN 978-0-06-207863-6. pp. 256–257
15. Jesus Now and Then by Richard A. Burridge and Graham Gould (2004) ISBN 0802809774 p. 34
16. Ehrman, Bart (2012). Did Jesus Exist?: The Historical Argument for Jesus of Nazareth. New York: HarperCollins. ISBN 978-0062206442.
17. Theissen, Gerd; Merz, Annette (1998). The Historical Jesus: A Comprehensive Guide. SCM Press. ISBN 9780334026969. OCLC 38590348
18. Bruce, Frederick Fyvie (1974). Jesus and Christian Origins Outside the New Testament. London: Hodder and Stoughton. ISBN 978-0-80281-575-0.
19. Josephus. The Antiquities of the Jews. Book 18:3 and Book 20 9:1
20. Tacitus. Annals. Book 15. Chapter 44.
21. The Death of Peregrine, The Works of Lucian of Samosata. Translated by Fowler, H W and F G. Oxford: The Clarendon Press. 1905.
22. Eddy; Boyd (2007). The Jesus Legend: A Case for the Historical Reliability of the Synoptic Jesus Tradition. Baker Academic. p. 127. ISBN 978-0-8010-3114-4.
23. Thurén, Torsten. (1997). Källkritik. Stockholm: Almqvist & Wiksell.
24. Julius Africanus, Chronography, 18:1
25. Ante-Nicene Fathers. Volume VIII. Memoirs of Edessa And Other Ancient Syriac Documents. A Letter of Mara, Son of Serapion