I worked with a guy about 9 years ago, who thought "the wager" was his killer-death-blow. Until I told him that "I can't be wrong, my horoscope said I'd be right all this month".
He nearly wet himself and said "You reject God, yet you believe that rubbish?" and laughed superciliously.
Which gave me the opener of "You question astrology, but have you ever questioned God?"
I resisted adding "Check-mate". I bumped into him a couple years ago, it appears he did eventually question his god and his beliefs. He's still a bit of a prick though.
"What if you're wrong?"
In a good mood: "Well I wouldn't want to go to heaven or Valhalla with the likes of you anyways."
Bad mood: "At least hell is WARM."(especially used in winter)
Really, REALLY bad mood: "SMITE ME, OH MIGHTY SMITER!" And then I smirk, and continue with my grocery shopping or whatever I was doing, happier due to my little outburst.
Honestly, only by compacting his answer into a shorter response, without losing any of the thought, can you then have a better answer. I think Dawkin's answer was superb. I really don't think there's a better way to respond to it. I suppose I might say something like:
"Wrong about what? Christianity? Hindu? Islam? Scientology? FSM? Satanism?.....If any one of the corresponding 'gods' is true, then what are my chances of picking the right one? What are yours? What if you're wrong? You have just as much chance at failure."
To me that is still kind of the same as Dawkins' answer.
"Why would I be willing to trade my whole life for a lottery ticket?"
"What if you made a mistake by not spending your whole paycheck on lottery tickets?"
"Believing out of fear is not sincere belief and is therefore invalid according to the Bible."