There are more attestations to back up the Greek New Testament than any other classical antique writings. The time gap between the original manuscripts and the extant ones is less than the most believed historical writings. Moreover, there are more extant (by a humiliating number, as you will see to come) writings and manuscripts of the N.T. than any other historical writing.

(Much of the following information was taken from New Evidence That Demands a Verdict, by Josh McDowell)

"To be skeptical of the resultant text of the New Testament books is to allow all of classical antiquity to slip into obscurity, for no documents of the ancient period are s well attested bibliographically as the New Testament." ­ John Warwick Montgomery

"Perhaps we can appreciate how wealthy the New Testament is in manuscript attestation if we compare the textual material for other ancient historical works. For Caesar's Gallic Wars (composed between 58 and 50 B.C.) there are several extant MSS, but only nine or ten are good, and the oldest is some 900 years later than Caesar's day. Of the 142 books of the Roman history of Livy (59 B.C.­A.D. 17), only 35 survive; these are know to us from not more than 20 MSS of any consequence, only one of which, and that containing fragments of Books III ­ VI, is as old as the fourth century. Of the 14 books of the Histories of Tacitus (c. A.D. 100) only four and a half survive; of the 16 books of his Annals, 10 survive in full and two in part. The text of these extant portions of his two great historical works depends entirely on two MSS, one of the ninth century and one of the eleventh.

Even so, there are historians who wrote about Jesus and the impact he left by doing so many wonders. If in reality the wonders and miracles that Jesus and His disciples claimed to do were not true, then the people would know it, and His philosophy would not have been passed on or proclamations of such absurdity. Every of the 12disciples besides one, if their claims were not true, died for a lie, and they would have to have known it to be a lie. They claimed to have seen Jesus risen from the dead and heal many thousands of people. If 12 or more would have made this up, and wanted to spread stories, would they have gone far enough to have died for something they knew not to be true? (and they wouldn't have the boldness to die either, for they wouldn't believe either that they were sealed with the destination of eternal paradise).

Before Jesus died, the disciples still didn't believe fully of the truthfulness that was in Jesus. They were cowards:

"And, behold, there arose a great tempest in the sea, insomuch that the ship was covered with the waves: but he was asleep. [25] And his disciples came to him, and awoke him, saying, Lord, save us: we perish. [26] And he saith unto them, Why are ye fearful, O ye of little faith? Then he arose, and rebuked the winds and the sea; and there was a great calm." - Matthew 8:24-26

"Now Peter sat without in the palace: and a damsel came unto him, saying, Thou also wast with Jesus of Galilee. [70] But he denied before them all, saying, I know not what thou sayest." - Matthew 26:69-70

After the resurrection, the disciples became bold and witnessed throughout the whole region. They were killed for their testimonies and up to the death they took beatings and imprisonments.

"As it is written, For thy sake we are killed all the day long; we are accounted as sheep for the slaughter." - Romans 8:36

"Now when they saw the boldness of Peter and John, and perceived that they were unlearned and ignorant men, they marvelled; and they took knowledge of them, that they had been with Jesus." - Acts 4:13

The message of the Gospel and of the testimony of Christ and the disciples were know to be true in the rest of the world, for they (the public) saw even with their own eyes the wonders they did. The writings would not have been allowed to be passed on as truth if rulers and counsels didn't know it to be true also.

Acts 4:5-16: "And it came to pass on the morrow, that their rulers, and elders, and scribes, [6] And Annas the high priest, and Caiaphas, and John, and Alexander, and as many as were of the kindred of the high priest, were gathered together at Jerusalem. [7] And when they had set them in the midst, they asked, By what power, or by what name, have ye done this? [10](Peter talking) Be it known unto you all, and to all the people of Israel, that by the name of Jesus Christ of Nazareth, whom ye crucified, whom God raised from the dead, even by him doth this man stand here before you whole. [14] And beholding the man which was healed standing with them, they could say nothing against it. ..[16] Saying, What shall we do to these men? for that indeed a notable miracle hath been done by them is manifest to all them that dwell in Jerusalem; and we cannot deny it."

The Historian Josephus who lived (c. A.D. 37-100) recorded many of the testimonies that were passed down and interviewed many of the same people and relatives of those who had contact with Jesus and the disciples. They assured of the validity of the testimonies of the Bible.

Pontius Pilate, the procurator and governor of the area the Jesus was crucified in. He, even in the Bible admits that Jesus did nothing wrong, and that he marveled greatly at Him:

"And the governor said, Why, what evil hath he done? But they cried out the more, saying, Let him be crucified." Matthew 27:23

There was a report that Pontius had to write about Jesus to the king of the nation, Caesar. In the report it gives the account of the conversations between Jesus and Pilate, and the opinions and thoughts of Pilate. In this report, Pilate confirms the miracles that Jesus did, and seems to believe that Jesus was telling the truth. Later on, it shows evidence that Pontius believed that Jesus was the Son of God.

Really Great Links to learn of evidences of God and Jesus: