Objective evidence for the existence of Jesus Christ?

[Pizza]

But that information which convinces the experts is available on request. That's the point. 

When defending evolution, biologists don't say "shut up, we're the experts and we say so". They bring evidence to the table to show why they are convinced. 

That's what historians do and you just hand wave it away because the evidence isn't ideal. Reliability of evidence isn't all or nothing, even propaganda like the Bible and liars can tell us something about the past figures. That's just the way of the real world. You are not going to get 100% reliable sources. No one is claiming that we have to swallow every claim made without asking questions and doubting. To use your isolated island thought experiment: If Fox News said Obama is the presidentof USA, I wouldn't say I guess Obama doesn't exist.