Why do you believe?

[Tea Earl Grey Hot]

So the difference is how many people witnessed the claim? What's the criteria?

You've answered it. More eye witnesses of a claim leaves us with greater evidence. Witness equals evidence I thought you knew that?

What eye witnesses accounts?

All you have are the gospels written many decades after the events they are supposed to depict, often having widely contradictory accounts. We don't know who really wrote these gospels (the names only come through late guess work of later Christians).

Then you have Paul who's only connection to Jesus was through a "vision" (hallucination?). There's a reference to I think "500" witnesses to the resurrection but that easily can be made up. No body would have bothered to travel all the way Jerusalem to check up on these supposed witnesses to see if they really saw what whatever evangelist said they did.

Even if one or two people decided to play detective and go all the way to Jerusalem to interview somebody who supposedly saw the resurrection, and then found those accounts to false, that wouldn't stop the growth of Christianity. Said detectives could be claimed to be lying or spiritually blind by the evangelist.