Evidence of the existence of a god would be something like having god meet me in a coffee shop and sharing a hot beverage while we talk about all of the vile, horrible things he has allowed to happen on this earth. More importantly, just meeting god in the coffee shop so I can meet him face to face would work. He shows up and I'll actually believe. But he's gotta bring some form of ID, otherwise, he could just be some hobo coming in off the street to take advantage of a free hot beverage.
Disclaimer: I am only responsible for what I say, not what you choose to understand.