Do you believe in a God who responds reliably to prayer? Do you believe in the supernatural? Do you know anyone who has paranormal powers? Do you think those guys on TV really get messages from dead people?
James Randi's One Million Dollar Paranormal Challenge is still in effect - a million smackeroos to anyone who can show, under proper observing conditions, evidence of any paranormal, supernatural, or occult power or event.
However, it will end in two years. Get your application here.
Now remember - don't burden them with theories, philosophical observations, previous examples, anecdotal evidence or other comments! They are only interested in an actual demonstration. They also will not accept claims of the existence of deities or demons/angels, the validity of exorcism, religious claims, cloudbusting, causing the Sun to rise or the stars to move, etc. - just show them the evidence under controlled conditions.
I really think Pat Robertson should apply, since God has been talking to him about the results of the 2008 U.S. presidential election.
Or is your God so omnipotent that He can deliberately mess up the results of any experiment that any mere human can devise to demonstrate His power? What, He won't cooperate even if the money was to be donated to a good cause? That just doesn't seem nice.
He didn't respond positively to prayers for the recovery of over 1800 people undergoing heart surgery - in fact, He induced more complications in the people who knew they were being prayed for. Nor did He help heart patients being prayed for by Christian, Muslim, Jewish, and Buddhist groups in another study involving 748 subjects. Now that doesn't seem very kind and merciful - in fact, He seems pretty obstinate and cantankerous. "Gosh, Mr. Heart Patient, it's a darned shame that you were enrolled in that prayer study, because otherwise God surely would have responded to those intercessory prayers and you would have been fixed up right as rain. . . ."