Christianity's foundation

Paul tells the crowd in Athens,

God overlooked people's former ignorance about these things, but now he commands everyone everywhere to turn away from idols and turn to him.
For he has set a day for judging the world with justice by the man he has appointed, and he proved to everyone who this is by raising him from the dead.

Acts 17:30-31.

Paul talks elsewhere about the resurrection as essential to the faith he was teaching.

13 But if there is no resurrection of the dead, then not even Christ has been raised.
14 And if Christ has not been raised, then our preaching is in vain and your faith is in vain.
15 We are even found to be misrepresenting God, because we testified about God that he raised Christ, whom he did not raise if it is true that the dead are not raised.
16 For if the dead are not raised, not even Christ has been raised.
17 And if Christ has not been raised, your faith is futile and you are still in your sins.
18 Then those also who have fallen asleep in Christ have perished.
19 If in Christ we have hope in this life only, we are of all people most to be pitied.
20 But in fact Christ has been raised from the dead, the firstfruits of those who have fallen asleep.
21 For as by a man came death, by a man has come also the resurrection of the dead.
22 For as in Adam all die, so also in Christ shall all be made alive.

1 Corinthians 15

As far as Paul is concerned, this is the important stuff. Like most believers in Jesus, someone I have never met physically, or heard, or seen, or touched, I have periods of doubt. I agree with Paul's words, am I among the most pitied? Do I believe in a fairy tale? But I cannot shake the experience of those eyewitnesses of Jesus's resurrection. With the exception of John, they all died horrible deaths for their eyewitness accounts which they wouldn't recant. Paul says later in 1 Corinthians 15,

30 And as for us, why do we endanger ourselves every hour?
31 I die every day--I mean that, brothers--just as surely as I glory over you in Christ Jesus our Lord.
32 If I fought wild beasts in Ephesus for merely human reasons, what have I gained? If the dead are not raised, "Let us eat and drink, for tomorrow we die."

If the resurrection did indeed really occur then so many other things are possible.

• The other crazy stuff in the Bible might have really happened too
• The message in the Bible might really be from God
• God might be real
• The Creator might actually love me
• My life could be part of something greater and more significant than anything in history
• Death is not an end, but a transfer station

But how do I know all these things are true? I can only rely on eyewitnesses. There is no time machine to see things myself. I rely on the testimony of others all the time for so many things. National Geographic has pictures to document things around the world, of places I will never go to. It's possible those pictures are fakes. Movies fake places all the time. Sometimes even NG gets duped, like the Chinese feathered dinosaur fiasco. But the fraud eventually comes to light. No one ever produced Jesus' body from a grave to shut the early Christians up. There is no evidence that the death and resurrection of Jesus was a fraud.

Jesus's mother and friend John watched him die on the cross, but they were also early witnesses of his empty tomb. They also encountered him again, alive, with scars from his crucifixion, eating with them, talking with them, walking with them, instructing them as he had before.

And this small group from a small ethnic group in the center of an empire changed it with this message, despite the violent reprisals of that empire. If they only recanted, their lives would not have ended so tragically. They did not trade their message for wealth or sensual pleasures, as many other prophets (so-called) have done repeatedly in history.

John the Beloved was almost killed in boiling oil. At that point, he would have welcomed death. But he lived and did not change his testimony.

There is no other explanation that that the resurrection of Jesus really happened. Going back to the verse at the top, this proves who he is, the Savior and the Judge of the world, and the world will only be saved by him if they repent and turn to him.

In Paul's letter to the Romans, he makes the acceptance of the fact of the resurrection essential in the process of conversion

9 For if you confess with your mouth that Jesus is Lord and believe in your heart that God raised him from the dead, you will be saved.
10 For it is by believing in your heart that you are made right with God, and it is by confessing with your mouth that you are saved.
11 As the Scriptures tell us, "Anyone who believes in him will not be disappointed. "

Romans 10

The resurrection changed everything. I know this is the Christmas season still, but the advent was only so the death and resurrection could happen. We don't believe the baby Jesus saves us. No, we believe we are saved by the risen Lord.

update: I think this level of response from multiple eyewitnesses addresses this atheistic critique of eyewitness testimony.