Strength in Numbers (and Age)

Most ancient works of literature survive on fewer than a dozen copies—there are nearly 15,000 manuscripts of the New Testament. Homer's Iliad comes in a distant second place, with 643 surviving manuscripts, and Plato's work squeaks by with only 7.
Also, most surviving manuscripts of other ancient works date 1,000 years or more from the original. The New Testament gap is an unusually short 25 years. The earliest undisputed manuscript—the John Reynolds fragment—was found in Egypt and has been dated between A.D. 117-138.

Norman L. Geisler, Frank Turek

Incombustible Content

Even if every manuscript of the New Testament had been destroyed in ancient times, we'd still be able to piece it together. The church fathers {early and influential Christian theologians, teachers, and writers} of the second and third centuries quoted the New Testament so much—36,298 recorded times—that all but eleven verses can be reconstructed just from their quotations.

William Nix, Norman Geisler

Queasy Thomas?

One objection to the resurrection complains that Jesus only appeared to people that already believed he'd return. Actually, after his death, none of Jesus's followers any longer believed that he really was the messiah, let alone in any sense divine. They denied him after his arrest and went into hiding after he was killed. They had no expectation that a messiah would die, and they certainly weren't expecting him to be crucified. The accounts mention specifically the reactions of two witnesses—Paul and Thomas—who were in particular not eager to be convinced of such an appearance.

John 20: 24-28:
Now Thomas (called Didymus), one of the Twelve, was not with the disciples when Jesus came. So the other disciples told him, "We have seen the Lord!"
But he said to them, "Unless I see the nail marks in his hands and put my finger where the nails were, and put my hand into his side, I will not believe it."
A week later his disciples were in the house again, and Thomas was with them. Though the doors were locked, Jesus came and stood among them and said, "Peace be with you!" Then he said to Thomas, "Put your finger here; see my hands. Reach out your hand and put it into my side. Stop doubting and believe."
Thomas said to him, "My Lord and my God!"

N.T. Wright

Resurrection: Just as Weird Back Then

If the disciples simply saw or thought they saw someone they took to be Jesus, that by itself would not have generated the stories we have. Everyone in the ancient world took it for granted that people sometimes had strange experiences involving encounters with the dead, particularly the recently dead. They knew at least as much as we do about such visions, about ghosts and dreams—and the fact that such things often occurred within the context of bereavement or grief. They had language for this, and it wasn't resurrection. However many such visions they'd had, they wouldn't have said Jesus was raised from the dead; they weren't expecting such a resurrection.

N.T. Wright