Christians across the world are celebrating the bodily resurrection of Jesus Christ from the dead 2,000 years ago, a claim so outrageously bold that some nonbelievers wonder how anyone could believe it. Yet billions of Christians have based their lives on it for 20 centuries.

Breitbart News has reported a series on three core Christian beliefs. First is the Christmas story of God becoming man around 4 B.C. as Jesus of Nazareth, born in Bethlehem in Israel, and living a perfect life as a mortal man.

Second is the Good Friday story of Jesus as “the lamb of God who takes away the sin of the world” (John 1:29), a person who claimed to be God, being tortured and then publicly executed by Roman soldiers on the hill of Golgotha outside Jerusalem, Israel’s capital then and now.

Third is Easter, that Jesus Christ was bodily resurrected on the third day from his execution, emerged from the grave, and spent weeks with his disciples before ascending into heaven.

This is perhaps the most extraordinary claim of the Christian faith, and one that puzzles many critics of Christianity as to whether Jesus’s first followers were certifiably insane. People are born all the time, and people can debate whether a particular ordinary-looking child is actually Almighty God in the flesh. People also die all the time, including by public executions, and people can debate about whether some cosmic reconciliation was taking place through the death of a particular person.

However, people who are verifiably dead do not come back to life days later. It never happens. What really happened in A.D. 30 has been one of the most debated events in history.

Jesus was beaten, whipped, tortured, nailed to a cross, hung there for hours, then when it was time to kill all three prisoners being crucified that day, his executioners thought he was dead, but thrust a spear into the center of his abdomen just to make sure, causing blood to pour out of his abdomen. The Roman soldiers involved were experienced and professional executioners, and it seems clear that they succeeded.

The body of Jesus was buried on Friday. His disciples, a group of ordinary Jewish men and women, ran and hid rather than fight or proclaim that Jesus’s teachings had a meaning that survived his death. They were heartbroken and shattered, not trying to press the agenda they espoused when their teacher was alive. They immediately went back to their lives as fishermen and tradesmen.

But then on Sunday they became a group of fanatics, declaring the most unbelievable claim that Jesus of Nazareth had physically risen from the dead. Over a dozen of his followers claimed to have spent extended times with him after his resurrection, including placing their hands in his deadly wounds and eating bread and fish with him. Up to 500 of them claimed to have seen him in the following weeks. After those weeks, his closest followers said that he commissioned them to spread his gospel across all the world, then rose before their eyes into heaven.

His followers were ostracized from society, and brutally opposed. Many were imprisoned and publicly executed for publicly and passionately teaching these things. But they kept going, with their central point being that their master had conquered the grave, and that they therefore had nothing to fear. They rejoiced in their sufferings, and thousands were converted under their teaching.

Jesus’s personal attendants, called the apostles, spread throughout Europe, Africa, and Asia carrying this message of the gospel. One of the chief persecutors of this new church, Saul of Tarsus, claimed that Jesus physically appeared to him, struck him temporarily blind, and this Jewish religious teacher changed his name to Paul and became the most prolific writer expounding Jesus’s teaching. Paul’s works comprise roughly half of the New Testament.

All of these apostles except one met violent deaths, yet adhered to their central message – their gospel – until those untimely ends, that the God of the universe had come to earth in the form of a man, died to pay the price for humanity’s sins against the laws of a holy God, then was physically resurrected from the dead and paves the way to eternal life for everyone who would turn to him in faith.

Years of the apostle’s activities are recorded in the Bible in the Book of Acts. But what do Christians believe happened on that epic day that they say changed the world forever?

The events of Jesus’s life and death are recorded in the Bible’s four gospels: Matthew, Mark, Luke, and John.

From the Gospel according to John, Jesus’s closest friend, who simply referred to himself as “the disciple Jesus loved”:

Now on the first day of the week Mary Magdalene came to the tomb early, while it was still dark, and saw that the stone had been taken away from the tomb. So she ran and went to Simon Peter and the other disciple, the one whom Jesus loved, and said to them, “They have taken the Lord out of the tomb, and we do not know where they have laid him.” So Peter went out with the other disciple, and they were going toward the tomb. Both of them were running together, but the other disciple outran Peter and reached the tomb first. And stooping to look in, he saw the linen cloths lying there, but he did not go in. Then Simon Peter came, following him, and went into the tomb. He saw the linen cloths lying there, and the face cloth, which had been on Jesus’ head, not lying with the linen cloths but folded up in a place by itself. Then the other disciple, who had reached the tomb first, also went in, and he saw and believed; for as yet they did not understand the Scripture, that he must rise from the dead. Then the disciples went back to their homes. But Mary stood weeping outside the tomb, and as she wept she stooped to look into the tomb. And she saw two angels in white, sitting where the body of Jesus had lain, one at the head and one at the feet. They said to her, “Woman, why are you weeping?” She said to them, “They have taken away my Lord, and I do not know where they have laid him.” Having said this, she turned around and saw Jesus standing, but she did not know that it was Jesus. Jesus said to her, “Woman, why are you weeping? Whom are you seeking?” Supposing him to be the gardener, she said to him, “Sir, if you have carried him away, tell me where you have laid him, and I will take him away.” Jesus said to her, “Mary.” She turned and said to him in Aramaic, “Rabboni” (which means Teacher). Jesus said to her, “Do not cling to me, for I have not yet ascended to the Father; but go to my brothers and say to them, ‘I am ascending to my Father and your Father, to my God and your God.’” Mary Magdelene went and announced to the disciples, “I have seen the Lord”—and that he had said these things to her. On the evening of that day, the first day of the week, the doors being locked where the disciples were for fear of the Jews, Jesus came and stood among them and said to them, “Peace be with you.” When he had said this, he showed them his hands and his side. Then the disciples were glad when they saw the Lord. Jesus said to them again, “Peace be with you. As the Father has sent me, even so I am sending you.” And when he had said this, he breathed on them and said to them, “Receive the Holy Spirit. If you forgive the sins of any, they are forgiven them; if you withhold forgiveness from any, it is withheld.” Now Thomas, one of the Twelve, called the Twin, was not with them when Jesus came. So the other disciples told him, “We have seen the Lord.” But he said to them, “Unless I see in his hands the mark of the nails, and place my finger into the mark of the nails, and place my hand into his side, I will never believe.” Eight days later, his disciples were inside again, and Thomas was with them. Although 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, and see my hands; and put out your hand, and place it in my side. Do not disbelieve, but believe.” Thomas answered him, “My Lord and my God!” Jesus said to him, “Have you believed because you have seen me? Blessed are those who have not seen and yet have believed.” Now Jesus did many other signs in the presence of the disciples, which are not written in this book; but these are written so that you may believe that Jesus is the Christ, the Son of God, and that by believing you may have life in his name. John 20:1–31 (ESV).

Two thousand years later, more than a billion human beings identify as Christians. Hundreds of millions across the globe are observant and devout Christians, including tens of millions of the faithful in the United States. This belief in the resurrection of Jesus on Easter Sunday is the cornerstone of their faith and the foundation of how and why they live their lives.

Christians do not say that even if the resurrection never happened that it is all worth it because of the value of Jesus’s moral teaching and example. To the contrary, the Apostle Paul wrote, “If Christ has not been raised, then our preaching is in vain and your faith is in vain. … your faith is futile and you are still in your sins. … If in Christ we have hope in this life only, we are of all people most to be pitied.” 1 Corinthians 15: 14, 17, 19 (ESV).

Twenty centuries after that day, people are still talking and debating about what really happened.

Ken Klukowski is senior legal editor for Breitbart News. Follow him on Twitter @kenklukowski.