The experience of God has to be a precursor to the language and communication exchange, not the other way around. God is a personal God just as much as a universal God. People who have not connected with their personal God are never going to find that connection through these semantic discussions, where meaning is sought and constantly debated. You can't see the universal God, the God-in-Everything, unless you connect with God as individuated within you. Even this is a false dichotomy... they are one thing, but for the sake of discussion.
On the other hand, people who have connected to their personal God, can talk about themselves, even across language barriers, because the underlying connection is trusted and understood. I know what you're talking about and you know what I'm talking about because you and I are one.
I highly recommend people do a silent retreat in nature at least once in their lifetime. Go to a lodge or go camping, five days minimum, longer is better. Don't go for recreation. Go with the intention of connecting. Don't say a word, don't bring books, just be. My strong experience and understanding is that everyone has experienced God, no matter who they are or their creed. Not everyone talks about it. Not everyone can talk about it. Not everyone even identifies it as "God" because "God" is a word with many associations. They may call it any number of other things, or call it nothing. It doesn't require a word to be valid. The fact is, when you begin to see everything as part of you, and you as part of it, you'll see that God dwells in you, as you. There are no separations.
My point is... we are putting the cart ahead of the horse when we talk about proofs. Everyone has an individuated, personalized process with "God". It's happening right now. Forget the politics, the religion, the witless prattle... just go into nature and shut your mouth. More importantly, shut your monkey mind. Just be. That is "God", or whatever you choose to call it. It's there, it's all-permeating. It requires you to do nothing to get it. It is pure presence and you can relate to it, as it.
That's why these talks about proofs are so challenging. If you want proof then just say and do nothing.