@ Khandro - I haven't read all the answers to your OP yet= but could you pretty please point to where Richard Dawkins has ever categorically stated that god cannot possibly exist? Citations or links perfectly acceptable.
I am betting you cannot.And we have been down this track before, too, I seem to recall.
It is not as if he was forced into recanting some position of complete and utter denial by quality of the argument; rather, like any good scientist, he recognises it would be scientifically irresponsible to make such categoric statements for which we cannot provide objective empirical evidence either four or against.
He graded levels of theism and atheism - from 7 being 100% certain there was a god or 100% certain there wasn't, down to level 1 which was essentially agnostic. And he put himself ( and always has put himself) at level 6.
Certainly based around what i have seen of the last debate between the 2, I thought Richard Dawkins made the better points.
http://www.councilofexmuslims.com/index.php?topic=19892.0