Eyewitness accounts of human interaction with Him have been recorded and preserved for us in the Bible and are still recorded today.Wait a second George Burns look alike. How does he show up and say I am here? A voice from the clouds? An old bearded dude glowing? How does he show he is a god? Perform a miracle? Answer properly previously unanswered questions? How he used magnets and string to create the dinosaurs?
But does such documented testimony satisfy skeptics? It never has, and it never will.
Even if God Himself appeared & performed miracles, you'd probably say He's an alien or something & make fun of theists for "twisting the truth".
Some of the people who knew of Christ's miracles later shouted for His blood. That would've been you.