Today is the day Christians remember Jesus rising from the dead.
Initially, several women who went to put spices and potions on the body found the tomb Jesus was laid in empty. They found the Roman Guards had fainted, the heavy stone rolled away, (Mark 16.4) and Jesus’ burial clothes in a pile (John 20.6). They also saw one or two men, shining, who asked them why they were looking for the living one in the place of the dead. The men told the women, “Go and tell his disciples!’ Luke 24.5
So, they went and reported what they had seen and heard. But the women’s story “seemed to [the disciples] as idle tales.” Luke 24.11 This was from women after all. Women gossip. In that time and culture, women were not reliable witnesses.
But two of the disciples, Peter and John, (John 20:2-3) ran to the tomb and found it exactly as the women had said, minus the angels. But they weren’t yet convinced that Jesus had risen from the dead. They went back and told the others.
Later that day, two of Jesus’ followers were walking along the road to a village named Emmaus. You can read the rest of the account in Luke 24. It includes Jesus eating boiled fish in his resurrection body.
According to someone who was alive at that time, (1 Corinthians 15.6) Jesus later appeared to 500 of his followers at one time. They heard and saw Jesus. Hallucination can happen to one person, but for 500 people to experience the same hallucination is not feasible. These people went on to bear witness about the things they had seen and heard, although in many cases they were killed for their testimony because it was so unpopular.
Acts 2 also compares Jesus to King David. David died and was buried and the Israelites still had his tomb, but he prophesied about Jesus rising again.