When you're making an argument about scholarship, Wikipedia should not be your go-to source.Unless you merely wish to preach to the converted, yes, you do. That he refuses (and uses such a poor example) leaves him wide open to attack that he does not understand what he is arguing against. Understanding aids in any form of combat, whether you fight with weapons or words.
Also, Dawkins doesn't seem to be that good with his scholarship, since his assertion that Christ, as a historical figure, almost certainly did not exist is based on the assertion of someone who is not a historian. Even wikipedia suggests it to be true:
http://en.wikipedia.org/wiki/Historical_Jesus .
The idea of Christ as a myth is rejected by Bible scholars and historians: http://en.wikipedia.org/wiki/Jesus_myth_hypothesis#Scholarly_response
Hmmm... I wonder who to listen too...
And what do his opinions on the existence of a historical figure have to do with his ideas on the development of life on our planet? If you were debating him on the history of the last two thousand years, it might be relevant, but as it is it has zero impact either way.