Like Mark, Matthew, Luke, John and Paul?
If Mark was an 'eyewitness' why would he need to relate what Peter said? (cf. Eusebius and Papias)
And if Matthew was an eyewitness why would he have to borrow so much from non-eyewitness Mark?
Luke, to his credit, admits that he depended on the testimony of others. That and some liberal 'borrowing' of Flavius Josephus.
John, of 'Gospel of John' fame, seems to have a pretty high Hellenic-style Christology for an unlettered and unlearned Jewish fisherman. Not to mention that he didn't seem to care to much for Jews ...
Paul claims he was blined by a bright light and heard a voice. Stuff which now days usually gets you admitted to hospital, but I guess in the first century you could become a shaman and found a religion.
Therefore, if they went to their deaths voluntarily for the sake of His name, it is proof that they believed that Jesus was who He said He was and they were willing to die for what they knew, firsthand, to be true.
So what about the followers of Zeus, Aphrodite, or Apollo? Or the followers of Allah?
Jan Huss, the Waldensians, the Cathars all died for what they 'believed'.
Is that proof that they 'believed'? Certainly.
Is that proof that what they believed was true? Certainly not.
Nice cheap shot, but the difference is that before the bright light, etc., he had gone around dispossessing people of their homes and putting them to death: and AFTER the revelation became better behaved.
Kinda the opposite of those Moose-limb terrorists, BTW.
Cheers!