If someone claimed they can prove a negative they should have no problem proving God doesn't/does exist. Hint: Its not possible.
"I refuse to prove that I exist," says God, "for proof defies faith, and without faith, I am nothing."
"Aha," says man, "But the Babelfish is a dead giveaway, isn't it? It proves that you exist, and therefore you don't. Q.E.D."
Drew Garrett
Come on. Is this what you would attempt to try someone with. Whether or not they can prove God exists?
How about asking questions of those that have been following this case from the beginning, or asking them to source info or point you to a source, and after getting the information, coming to an informed conclusion?
I gather you have not read Mere Christianity by C.S. Lewis.