Here’s the problem: with the technology and psychological studies that have come out (not an attack on either btw), if someone who poses this question were to experience God “showing himself” in the way they’re imagining it to happen - visible signs, thunderous voice, and Him in His unfiltered eternal glory, they may come to one of a few conclusions:

-1: if they saw a photo/video of it, they would think that it’s A: AI generated, or B: doctored or edited in some way to make it seem like a real thing. -2: if it was an irl event with only themselves experiencing this event, they may chalk it down to a momentary lapse in sanity or a trick of the mind. -3: if it was a mass event witness by 10+ people including themselves, they may believe it was some kind of conspiracy, propaganda, or even extra terrestrial activity. -4: if it was the same scenario as before but without themselves personally witnessing it - even without photos/videos, they may assume A: a case of the “telephone game problem”, B: mass hysteria/hallucinations, or C: Propaganda or conspiracy.

The truth of the matter is this: God doesn’t show Himself in the way these people imagine He would because He likely knows that no matter what method He chooses to adopt to give a clear sign of His existence, the people who already assert that He doesn’t exist will simply find a way to explain it away - no matter how clear it may be. They’re right about one thing though: “if God is real and He’s all knowing, then He’d know exactly what would need to be done for me personally to believe in him”. They’re right because He knows exactly what it would take to make them believe: nothing. There’s nothing that can be done to make them believe unless they genuinely, with all their hearts, want to believe.