One of the "biased" sources - Luke - is widely regarded by people who know what they're talking about (like Sir William Ramsay who spent a lifetime digging up the Middle East) as the finest, most accurate historian who ever lived.
The fact that the first written accounts of Jesus appeared only decades after his execution is extraordinary to scholars of ancient literature who are used to dealing with gaps of many _centuries_, sometimes even a millenium. I can't remember offhand what the earliest copy we have of Tacitus is for example but I think it's a good 800 years after he wrote it.
When I apply the same methods of the Jesus mythers to Alexander the Great, Julius Caesar, Tacitus, Mohammed and even Abraham Lincoln, guess what? None of them ever existed either.
You need a great deal of hand-waving, special pleading and outright dishonesty to be a myther. Robin Lane Fox, who is certainly no Christian, is at least honest when he reads the account of John and concludes that it's an eyewitness account. Would that Dawkins and Price had the same integrity.
Wikipedia has a decent overview of this at http://en.wikipedia.org/wiki/Jesus_myth_theory