In 1 Corinthians 15:5-8, Paul writes, “and that he (Jesus) appeared to Cephas, and then to the Twelve. After that, he appeared to more than five hundred of the brothers and sisters at the same time, most of whom are still living, though some have fallen asleep. Then he appeared to James, then to all the apostles, and last of all he appeared to me also, as to one abnormally born.”
These verses demonstrate that Jesus’s resurrection was not a hoax, a lie, or an hallucination.
Jesus not only appeared to multiple people, he did so on several occasions. While he didn’t stay long—he ascended after forty days (Acts 1:3)—Jesus helped Peter forgive himself, taught the apostles and gave them instructions, and even ate with them.
And maybe most important was that he appeared to so many people.
That’s one of the points that Paul makes in these verses is that most of those who saw Jesus after his resurrection were still alive. In other words, double check his claims. Go ask them. He wasn’t afraid of being fact-checked.
The evidence for the resurrection was there and he pointed his readers straight to it.