If God does exist, then the very fact that humans know of his existence means that some form of proof has been offered and accepted.
If God does exist, then enough proof has been given to convince 95% of the world’s population at any time in history.
Those who do not believe in God claim the need for proof; those who do believe in the existence of God already have the proof they need.
"Thinking Eternally, Acting Locally." - Neal August