Apples and oranges...
http://www.asktheatheists.com/questions/1788-do-atheists-deny-the-existence-of-socrat/
One answer there was this:
Eric_PK
It’s very simple.
That Socrates existed is not an extraordinary claim; he is said to have been an excellent teacher and philosopher.
That somebody named Jesus existed is not an extraordinary claim.
That he was the son of god, was raised from the dead, and performed miracles – not(sic) that is an extraordinary claim.
Or, to put it another way, if Socrates did not exist, it’s not a big deal to my worldview. But if Jesus did not exist – or was not a god – it’s a huge deal to the christian worldview.
So, to summarize:
Socrates: Ordinary claim, minimal effect on my worldview.
Jesus: Extraordinary claim, huge effect on the christian worldview.
That is why they are different.