God has all the capability to not to leave any evidence for men, if He for a reason decides to hide from humans. If He has a will to hide from humans but humans somehow have acquired the empirical evidence of His existence then God is thus not all powerful as He failed to hide from men when He would like to.
So the next question for men to ask is,
by the current fact of status a God didn't show up to humans so there's no God if a self claimed God doesn't present the good reason why He has to hide behind. If a God didn't provide the answer for such an argument, the chances are He's either not a God or He doesn't care about humans. You can't get to an sincere answer of your future from such an indifferent God who chose to hide behind but failed to provide a good reason.
In Christianity, God has a covenant for men, which says men need to be saved by faith. A covenant needs to be abide by both sides. God thus won't show up to humans or else He Himself violates the covenant with the consequence that men can no longer be saved by faith. Do other religions provide a similar answer why God has to hide behind especially when it is said that a hell is waiting for humans?
The next question,
If God has a good reason to hide from humans completely then how can humans possibly get to know a future from this hidden God at all? There must be a way in between so that we can continue our journey of seeking. This "midway" is closed tied to the next most efficient way for a truth to convey, which may be be reckoned by humans.
In this reality, humans read facts from testimonies instead of evidence, such as history, such as daily news and even science. We don't dig evidence before we get to all kinds of facts. That's why among the 100% humans know for a fact that black holes exist, 99% of them don't have the evidence. We don't rely on evidence to get to this piece of scientific fact (may be to your surprise)! In the end, the majority of humans get to this fact by means of the testimonies of our scientists. We deemed their witnessing as trustworthy and credible.
Same the same, you can't basically prove history as it is made up of human testimonies. George Washington said <put whatever quote here>. How can you evidence that he actually said so? That piece of info (on what Washington said) is from testimonies and can hardly be evidenced. However somehow it remains the only way for humans to get to this piece of fact. Unlike a scientific fact which can repeat infinitive number of times in front of us, historical facts we acquire from testimonies may not be proved at all.
If God is true and He has a good reason to hide, thus all we can acquire are historical facts which can only be conveyed through human testimonies. He shows up to the chosen eyewitnesses for their testimonies to flow then for the rest of human kind to believe with faith. That's how it works.
How can you tell that an invisible entity is God, even when He's encountered by an eyewitness? There are two things men usually cannot do as they are not lying within humans' capability, 1) tell a future and 2) break our physics laws. God performs miracles and tells futures through the mouth of His chosen witnesses. That's why His witnesses are called the prophets, for a reason.
There are more I can reason with you, but next time...good luck.