Well, I always say that 11 of the 12 Apostles (After Judas) and countless others 1st century disciples chose death rather than deny the Resurrection and other miracles of Christ. Why would those men, St. Paul included, die for a lie? If they only meant to invent a power structure they could profit from, why die for it. What earthly profit is their in death, especially death for a lie? They claimed to be witnesses of His earthly life and ministry, and they died holding fast to that belief. I always thought that that was good proof.
Additionally, I would argue that the Resurrection is a true event. At the time of the Roman occupation of Israel, it was a capital crime for a soldier to leave his post or fall asleep at his post. After Christ died on the cross, Pilate assigned a centurion (commanding 100 troops) to guard the tomb so that His body would not be stolen. That amounted to 100 or so soldiers guarding the tomb. Would Christ’s body have been merely stolen? Wouldn’t that require each of the 100 or so soldiers to fall asleep or abdicate their post and in so doing risk severe reprimand or even death?
I hope this helps.