Actually if I claimed I know God exists for a fact then proof is necessary. If I say that his existance is likely or highly probable then I only have to demonstrate that. For example prophecy is one method. One example of the over two thousand is that the destruction of Tyre was predicted in detail including names and circumstances by God hundreds of years before it was completed. That if true and examples like it make an undeniable argument for the likely existance of God. Why don't we conclude that obviously science can't solve the issue and doesn't even make God less likely and see if the Bible can help out. Can you defend a lack of belief in the Bible?
This is where we have an unclear problem...
When you make the claim to the existence of something, the burden of proof is completely reliant on the one making the claim of existence.
If I had a box, and I said there was a spoon in the box, I would have to prove that there was a spoon in the box.
As an atheist. I recognize there is a universe. I don't claim there is a God.
You as a theist claim there is a universe and a God.
There is no reason to make such claims, so why do you?
Our science has taken claim for many things people claimed credit to God for.
Such as the tide, and the seasonal and daily cycles.
The bible reads like a realistic fiction. Where the characters and places seem plausible but the events are absurd. Its common in fables.
Why should I still believe in fairy tales?
Should I really believe that a donkey spoke or a army brought a city down by tooting their horns? Or that God would purposely kill every first born of an entire civilization?
This stuff has no place in reality.